Network Troubleshooting FAQ | FlowState Knowledge Base

01 My internet is slow — where do I start?

Slow internet has many possible causes. Work through these steps in order — each one narrows down where the problem is before you spend time in the wrong place.

Run a speed test Go to fast.com or speedtest.net from the affected device. Note the download speed, upload speed, and ping. Compare these numbers to what your ISP has contracted you to receive (check your bill or ISP account portal).
Test on multiple devices Run the same speed test on another device on the same network. If one device is slow but others are fast, the problem is isolated to that device — check its network adapter, drivers, and background processes. If all devices are slow, the problem is upstream (router, modem, or ISP).
Test wired vs. wireless Plug a laptop directly into the router with an Ethernet cable and run the speed test again. If wired is significantly faster than wireless, the issue is your Wi-Fi — see Section 7. If wired is also slow, the issue is your router, modem, or ISP.
Restart your modem and router Power off both devices, wait 30 seconds, then power on the modem first and wait for it to fully connect before powering on the router. This clears stale connections and refreshes your IP lease from the ISP. Many slow-internet complaints are resolved here.
Check for bandwidth-heavy background processes On Windows, open Task Manager (Ctrl+Shift+Esc) and click the Network column to sort by usage. On macOS, open Activity Monitor and click the Network tab. Look for unexpected processes consuming bandwidth — cloud backups, Windows Update, or video streaming apps running in the background are common culprits.

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Rule of thumb If your speed test shows less than 50% of your contracted speed consistently, and a modem restart doesn't fix it, call your ISP. If your speed test is fine but specific apps or websites are slow, the problem is local — keep reading.

02 Is it my router, modem, or ISP?

These three devices are often blamed interchangeably, but they are distinct failure points. Here is how to isolate which one is at fault.

What is the difference between a modem and a router?

Your modem connects your home or office to the ISP's network. It translates the signal from the cable, fiber, or DSL line into an Ethernet signal. Your router takes that Ethernet signal and distributes it to multiple devices — wired and wireless. Many ISPs supply a combined modem/router unit (called a gateway). If you have one box, it is doing both jobs.

How do I tell if the modem is the problem?

Connect a laptop directly to the modem (or the WAN port of your gateway) with an Ethernet cable, bypassing the router entirely. Run a speed test. If speeds are normal here but slow through the router, the router is the problem. If speeds are still slow, the issue is the modem or the ISP line coming in.

Also check the modem's status lights. Most modems have an indicator for the upstream connection (labeled "Online," "WAN," or similar). If it is flashing or off, the modem has not established a link with the ISP — this is almost always an ISP-side issue.

How do I check if the ISP is having an outage?

Check downdetector.com and search for your ISP. You can also log into your ISP's customer portal from a mobile hotspot to check for reported outages in your area. Call your ISP's support line and ask if there are any known issues at your address.

From a command prompt or terminal, run a traceroute to a known server to see where packets stop:

# Windows
tracert 8.8.8.8

# macOS / Linux
traceroute 8.8.8.8

If packets get to your router (hop 1) but stop or time out at hop 2 or 3, the issue is at the ISP's infrastructure. If packets don't even reach hop 1, the issue is your local equipment.

My router's admin page is slow or unreachable — what does that mean?

If you cannot reach your router's admin interface (usually 192.168.1.1 or 192.168.0.1) from a wired connection, the router itself may be overloaded, crashed, or failing. Try a hard reset by holding the reset button on the back of the router for 10 seconds. If the problem persists after a reset, the router may need to be replaced.

03 Devices can't see each other on the local network

This is a common issue in small business environments. When devices on the same network can't communicate with each other, the cause is almost always one of the following: a firewall blocking local traffic, network discovery being disabled, devices on different subnets or VLANs, or a DHCP conflict.

How do I confirm two devices are on the same subnet?

On each device, check the IP address and subnet mask:

# Windows — run in Command Prompt
ipconfig

# macOS / Linux
ifconfig # or: ip addr show

Both devices need to have IP addresses in the same range and the same subnet mask. For example, 192.168.1.10 and 192.168.1.25 with a mask of 255.255.255.0 are on the same subnet. 192.168.1.10 and 192.168.2.10 are not — they cannot communicate directly without routing.

Devices are on the same subnet but still can't ping each other

The most common cause on Windows networks is the firewall blocking ICMP (ping) traffic. To test connectivity without ping, try accessing a shared folder or using telnet to a specific port.

To allow ping through Windows Defender Firewall temporarily for testing:

# Run in an elevated Command Prompt
netsh advfirewall firewall add rule name="Allow ICMPv4" protocol=icmpv4:8,any dir=in action=allow

If devices can communicate after this, add a permanent inbound rule for the specific traffic you need (file sharing, RDP, etc.) rather than disabling the firewall entirely.

Network discovery is on but I still can't browse to other computers

Windows network browsing relies on a service called Function Discovery. Make sure the following services are running on the machine you're trying to reach (services.msc):

Function Discovery Resource Publication
SSDP Discovery
UPnP Device Host

Also confirm that both machines are set to the same network profile (Private, not Public). Public profile suppresses discovery by design. Change this in Settings → Network & Internet → [your connection] → Network profile.

Could VLANs be separating my devices?

If you have a managed switch, it is possible devices have been placed on different VLANs intentionally or by misconfiguration. VLANs create isolated broadcast domains — devices on VLAN 10 cannot see devices on VLAN 20 without a Layer 3 router or inter-VLAN routing rule. Check your switch's port configuration and confirm all affected devices are assigned to the same VLAN. This is one area where a remote session with FlowState will save significant time.

04 VPN connected but can't reach internal resources

A VPN connection that shows as "Connected" does not automatically mean all traffic is routing correctly. These are the most common reasons internal resources are unreachable despite an active VPN.

How do I tell if it's a routing issue or a DNS issue?

Try accessing the internal resource by its IP address directly instead of its hostname:

# If this works:
ping 10.0.1.50

# But this doesn't:
ping fileserver.company.local

If the IP works but the hostname doesn't, the problem is DNS — your VPN client is not using the internal DNS server. If neither works, traffic is not being routed through the VPN at all.

VPN is connected but DNS doesn't resolve internal hostnames

When connected to the VPN, check which DNS servers your machine is using:

# Windows
ipconfig /all

Look for "DNS Servers" under the VPN adapter

The VPN adapter should be pointing to an internal DNS server (typically a domain controller — e.g. 10.0.0.1), not your ISP's DNS or a public DNS like 8.8.8.8. If it shows public DNS, the VPN's DNS push configuration is incorrect and needs to be fixed on the VPN server side.

A quick workaround while troubleshooting: manually query the internal DNS server:

nslookup fileserver.company.local 10.0.0.1

If that returns the correct IP, the server is working — only the DNS routing is misconfigured.

VPN routing — what is split tunneling and should I use it?

Split tunneling routes only traffic destined for internal networks through the VPN, while all other traffic (internet browsing, etc.) goes directly through your local ISP connection. Full tunnel routes all traffic through the VPN, including internet traffic.

If split tunneling is enabled and the internal subnet is not included in the split tunnel routes, you will not be able to reach it. Check the VPN client's route table while connected:

# Windows — run in Command Prompt
route print

Look for routes added by the VPN adapter (metric will typically be lower)

The internal subnet (e.g. 10.0.0.0/8 or 192.168.100.0/24) must appear in this table pointing to the VPN adapter for traffic to route correctly.

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VPN firewall rules Even with correct routing and DNS, a firewall on the internal network may block traffic from VPN client IPs. This is common in environments where the VPN server issues addresses from a different pool (e.g. 10.8.0.0/24) and the internal firewall only allows traffic from the LAN subnet. Confirm the internal firewall has a rule permitting VPN client IPs to reach the resources you need.

05 DNS resolution failures

DNS translates hostnames (like theflowstate.solutions) into IP addresses. When DNS fails, websites and internal resources become unreachable even though your network connection is fine. The symptom is usually a browser error like "Server not found" or "DNS_PROBE_FINISHED_NXDOMAIN."

How do I confirm it's a DNS problem and not a connectivity problem?

Try reaching a site by its IP address instead of its domain name. Google's main page is reachable at 142.250.80.46. If that loads in your browser but google.com doesn't, DNS is the problem, not your internet connection.

Also run a direct DNS query from the command line:

# Windows
nslookup google.com

# macOS / Linux
dig google.com

If this returns a timeout or "server failed" error, your configured DNS server is unreachable or not responding.

How do I flush the DNS cache?

Windows caches DNS responses locally. A stale or corrupted cache entry can cause resolution failures even when the upstream DNS server is working correctly. Flush it with:

# Windows — run in elevated Command Prompt
ipconfig /flushdns

# macOS Monterey and later
sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder

# Linux (systemd-resolved)
sudo systemd-resolve --flush-caches

After flushing, try the failing hostname again.

How do I change my DNS server to a public one for testing?

Switching temporarily to a public DNS server (like Google's 8.8.8.8 or Cloudflare's 1.1.1.1) is a fast way to confirm whether your ISP's or network's DNS server is at fault.

On Windows: Control Panel → Network Connections → right-click adapter → Properties → IPv4 → Properties → set Preferred DNS to 8.8.8.8.

If resolution works after switching, the problem is with your original DNS server (router, ISP, or internal DNS server). If it still fails, the problem is not DNS.

Could my hosts file be causing the problem?

The local hosts file is checked before DNS and can override DNS responses. A wrong entry here will cause a hostname to resolve to the wrong IP regardless of what DNS returns.

# Windows — location
C:\Windows\System32\drivers\etc\hosts

# macOS / Linux
/etc/hosts

Open this file in a text editor (as administrator on Windows). Look for any entries for the hostname that's failing. A legitimate file typically only has 127.0.0.1 localhost and ::1 localhost entries. Anything else should be reviewed.

06 Firewall is blocking legitimate traffic

Firewalls block traffic silently — they don't send an error back to the sender. This makes firewall issues look identical to network failures from the client's perspective. The key diagnostic question is: does the issue go away when the firewall is temporarily disabled?

How do I test whether the firewall is the cause?

Temporarily disable Windows Defender Firewall and try the failing connection again:

# Disable (run in elevated Command Prompt — for testing only)
netsh advfirewall set allprofiles state off

# Re-enable when done testing
netsh advfirewall set allprofiles state on

If the connection works with the firewall off, the firewall has a rule blocking it. Do not leave the firewall disabled — re-enable it and add a specific allow rule instead.

How do I find which firewall rule is blocking traffic?

Enable firewall logging to capture dropped packets:

# Enable drop logging (Windows Defender Firewall)
netsh advfirewall set allprofiles logging droppedconnections enable
netsh advfirewall set allprofiles logging filename "%systemroot%\system32\LogFiles\Firewall\pfirewall.log"

Then reproduce the blocked connection and check the log file at C:\Windows\System32\LogFiles\Firewall\pfirewall.log. Look for DROP entries that match the source IP, destination IP, and port you're trying to reach.

You can also check the Windows Event Viewer: Windows Logs → Security — filter for Event ID 5152 (dropped packet) or 5157 (blocked connection).

How do I add an allow rule for a specific port or application?

To allow a specific port inbound (e.g., TCP port 3389 for RDP):

netsh advfirewall firewall add rule name="Allow RDP" dir=in action=allow protocol=TCP localport=3389

To allow a specific application:

netsh advfirewall firewall add rule name="Allow MyApp" dir=in action=allow program="C:\Path\To\app.exe" enable=yes

You can also manage rules through the GUI: Windows Defender Firewall with Advanced Security → Inbound Rules → New Rule.

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Group Policy overrides local firewall rules In domain-joined environments, Group Policy may push firewall rules that override anything you set locally. If your rules don't stick after a reboot or gpupdate, check with your domain admin — the policy will need to be modified at the GPO level.

07 Wi-Fi drops intermittently

Intermittent Wi-Fi disconnections are frustrating because they are hard to reproduce on demand. The most common causes are channel interference, distance or physical obstructions, adapter power management settings, and DHCP lease issues.

How do I check for Wi-Fi channel interference?

If nearby networks are using the same Wi-Fi channel as yours, they will interfere with each other — especially on the crowded 2.4 GHz band. Download a free Wi-Fi analyzer app (Wi-Fi Analyzer on Android, or use the built-in Wireless Diagnostics on macOS) to see which channels neighboring networks are using.

Log into your router's admin page and change your Wi-Fi channel manually. On 2.4 GHz, use channels 1, 6, or 11 — these are the only non-overlapping channels. On 5 GHz, most channels are non-overlapping and interference is less common.

My laptop drops Wi-Fi but my phone stays connected

When one device drops but others stay connected, the issue is almost always the device's network adapter settings — not the router. The most common culprit on Windows laptops is the power management setting that lets Windows turn off the adapter to save power:

Open Device Manager (devmgmt.msc)
Expand Network Adapters and right-click your Wi-Fi adapter
Select Properties → Power Management
Uncheck "Allow the computer to turn off this device to save power"
Click OK and test

Also update the network adapter driver — go to Device Manager, right-click the adapter, and select Update driver. Outdated Wi-Fi drivers are a frequent cause of dropped connections.

Wi-Fi signal looks strong but connection still drops

Signal strength bars are not the full picture — signal quality (interference and noise) matters just as much. A strong but noisy signal will drop packets constantly. Run a continuous ping while the drops occur to characterize the problem:

# Ping your router continuously — note when drops occur
ping -t 192.168.1.1 # Windows
ping 192.168.1.1 # macOS/Linux (Ctrl+C to stop)

If you see Request timed out responses mixed in with normal replies, the connection is dropping at the radio layer before the DHCP lease even expires. Moving closer to the access point or adding a Wi-Fi extender or mesh node is often the right fix.

Could my DHCP lease be causing disconnects?

If your router's DHCP lease time is set very short (under 1 hour), devices may briefly lose connectivity during the renewal process. Check your router's DHCP settings and set the lease time to at least 8 hours for a stable office or home environment.

You can also assign a static IP to problem devices to eliminate lease renewal as a variable entirely. Do this either through the router's DHCP reservation table (preferred — it keeps the IP managed centrally) or by setting a static IP on the device directly.

08 When to call your ISP vs. when to call us

Knowing who owns the problem saves you from being bounced between support queues. Here is a clear breakdown:

Symptom / Situation	Who to Call	Why
No signal to modem / modem offline	ISP	Physical line or provisioning issue — outside your equipment
Confirmed ISP outage in your area	ISP	Nothing local to fix — wait for their restoration
Speed test slow even directly on modem	ISP	Speeds are measured at the ISP handoff point — their responsibility
Modem online, router not distributing IP addresses	FlowState	DHCP server config, router failure, or WAN config issue
Devices can't see each other on LAN	FlowState	Firewall, VLAN, or subnet configuration — local equipment
DNS failures (sites unreachable, names not resolving)	FlowState	DNS server config, hosts file, or router DNS settings
VPN not routing correctly to internal resources	FlowState	Routing tables, split tunnel config, or firewall rules
Wi-Fi dropping on specific devices	FlowState	Adapter drivers, power management, or AP configuration
Slow speeds through router but fast directly on modem	FlowState	Router performance, QoS settings, or firewall overhead
Intermittent drops affecting all devices at once	Either	Could be ISP line instability or router hardware failing — test both

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Still not sure? Start with us. A remote session lets us run diagnostics on your network in real time and tell you definitively whether the problem is your ISP or your local equipment — before you waste time on hold with your ISP for a problem that's actually in your router. Submit a support request here.

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