When the internet stops working in an office, everybody suddenly becomes a network engineer.

“The Wi-Fi is down.”

“The broadband is slow.”

“Microsoft 365 isn't working.”

“The server has disappeared.”

But these symptoms can have completely different causes.

A laptop can be connected perfectly to Wi-Fi while having no internet access.

The internet can work while DNS is broken.

One computer can have a problem while the rest of the office is completely healthy.

And sometimes what looks like an internet outage is actually a problem with one website or cloud service.

So before restarting every switch in the building, ask:

What exactly isn't working—and who is affected?

That question can reduce a complicated networking problem to something much easier to diagnose.

Before Troubleshooting: Work Out the Scope

Start with three questions.

Is it one device or everybody?

If one laptop is affected while 30 others work normally, your broadband connection probably isn't the first thing to investigate.

Look at the laptop.

If the whole office loses connectivity simultaneously, investigate shared infrastructure such as:

• firewall
• router
• switch
• access points
• DNS
• DHCP
• internet connection

Is it Wi-Fi, Ethernet or both?

If Ethernet works but Wi-Fi doesn't, the internet connection itself is probably functioning.

Investigate:

• access points
• wireless configuration
• signal
• interference
• Wi-Fi adapter

If neither works, look further upstream.

Is everything broken or just one service?

Try several unrelated services.

If:

Microsoft 365 doesn't work

but:

BBC, Google and other websites do

you probably don't have a general internet outage.

You may have a Microsoft 365, DNS, authentication or application-specific problem.

This basic isolation should happen before anything more complicated.

1. Connected to Wi-Fi but No Internet

This is one of the most confusing network messages:

Connected, no internet

It means the laptop has successfully established a wireless connection, but Windows cannot reach the internet.

The Wi-Fi itself isn't necessarily broken.

Possible causes include:

• router problem
• broadband outage
• DHCP failure
• DNS failure
• incorrect gateway
• VPN
• firewall
• captive portal

Check Another Device

Connect another phone or laptop to the same Wi-Fi.

If every device has no internet, investigate the network.

If only one device is affected, investigate that computer.

Microsoft recommends exactly this comparison because it quickly helps distinguish a PC-specific problem from a router or wider network problem.

Check the IP Address

Open Command Prompt and run:

ipconfig

Look at the active adapter.

You would normally expect an address appropriate to your network, such as:

192.168.1.57

or:

10.0.0.84

If you see something beginning:

169.254

that is an important clue.

Microsoft says an address in the 169.254.x.x range indicates that Windows could not obtain an IP address from the router.

That moves DHCP much higher up the suspect list.

2. IP Address or DHCP Problems

Most business computers obtain their network configuration automatically using DHCP — Dynamic Host Configuration Protocol.

DHCP can provide:

• IP address
• subnet information
• default gateway
• DNS servers

Microsoft recommends DHCP for normal TCP/IP configuration because it automatically assigns network settings to devices.

If DHCP fails, the computer may connect physically to the network but be unable to communicate properly.

Try Renewing the Address

Open Command Prompt as Administrator and run:

ipconfig /release

followed by:

ipconfig /renew

Then check:

ipconfig

Microsoft includes releasing and renewing the DHCP lease among its current Windows network troubleshooting steps.

If you repeatedly receive 169.254.x.x, investigate:

• DHCP server
• router
• VLAN configuration
• switch port
• Wi-Fi network configuration
• network adapter

For a business environment, dozens of devices simultaneously losing DHCP is very different from one laptop failing to obtain a lease.

3. DNS Problems

Here's a classic scenario.

You cannot open:

hgmssp.com

but networking appears to be working.

DNS may be the problem.

DNS translates names such as:

hgmssp.com

into IP addresses computers can use.

Without working DNS, the internet can appear broken even though connectivity itself is fine.

Test DNS Separately

Open Command Prompt.

Try:

ping 1.1.1.1

Then try:

nslookup hgmssp.com

These tests answer different questions.

If you can reach an external IP address but name lookups fail, DNS becomes a strong suspect.

You can clear Windows' local DNS resolver cache with:

ipconfig /flushdns

Microsoft includes flushing the DNS cache in its current Windows network troubleshooting sequence.

But don't change DNS servers randomly every time the internet feels slow.

First prove that name resolution is actually the problem.

4. Wi-Fi Is Slow or Keeps Dropping

Wi-Fi problems deserve their own diagnosis.

Common causes include:

• weak signal
• interference
• overloaded access points
• poor AP placement
• driver problems
• power management
• congested wireless channels
• unsuitable frequency band
• too many clients

Microsoft recommends trying another wireless frequency band where available when troubleshooting Wi-Fi performance and connectivity.

2.4 GHz vs 5 GHz vs 6 GHz

Broadly:

2.4 GHz

travels further and penetrates obstacles better, but tends to offer lower speeds and more interference.

5 GHz

usually provides higher performance with less range.

6 GHz

can provide excellent performance with compatible Wi-Fi 6E/7 equipment but has different coverage characteristics again.

Don't assume:

“Strong signal = good Wi-Fi.”

A laptop can show full bars while connected to a congested access point.

Don't Solve Business Wi-Fi With Endless Extenders

A growing business may eventually need properly designed:

• business access points
• wired backhaul
• appropriate channel planning
• VLANs
• central management
• sufficient AP density

Adding another cheap wireless extender every time somebody finds a dead spot can make the wireless environment worse.

5. Ethernet Is Connected but Slow

Ethernet normally provides predictable performance.

If a Gigabit-capable computer is only achieving around:

90–95 Mbps

check its negotiated link speed.

Go to:

Settings > Network & internet > Ethernet

Look for:

Link speed (Receive/Transmit)

If Windows reports:

100/100 Mbps

rather than:

1000/1000 Mbps

you have found an important clue.

Check:

• Ethernet cable
• wall socket
• patch panel
• switch port
• USB Ethernet adapter
• dock
• network driver
• negotiation

Microsoft recommends checking the physical Ethernet cable and trying another cable early in its Ethernet troubleshooting process.

A damaged cable can still work while negotiating at a lower speed.

So:

“It says connected”

does not prove the cable is healthy.

6. Duplicate or Incorrect IP Addresses

Every active device on a normal IP network needs an appropriate unique address.

Problems can occur when two devices are configured with the same static IP address.

Symptoms may include:

• intermittent connectivity
• one device knocking another offline
• printers disappearing
• server connections failing
• apparently random network behaviour

This is especially common where organisations manually assign static addresses without documenting them.

Better Approach

Use DHCP for ordinary endpoints.

For equipment requiring predictable addresses—such as:

• printers
• servers
• network equipment

consider centrally managed DHCP reservations or carefully documented static assignments where appropriate.

Avoid creating an office full of undocumented:

192.168.1.xxx

addresses that nobody remembers assigning.

7. VPN Connects but Nothing Works

A VPN introduces another network layer.

If everything works before connecting to the VPN but stops immediately afterwards, investigate:

• VPN routes
• DNS
• split tunnelling
• firewall policy
• proxy configuration
• VPN client
• remote gateway

Do not immediately reset Windows networking.

First establish:

Does the problem exist without the VPN?

Microsoft's Windows interface now clearly identifies recognised VPN connections, which makes separating ordinary Wi-Fi connectivity from VPN routing problems easier.

For business devices, don't permanently disable a required VPN simply because doing so restores connectivity.

Find the configuration problem.

8. The Whole Office Is Slow

This is where troubleshooting one laptop at a time becomes a waste of effort.

If everyone suddenly reports:

“The network is slow.”

look for shared infrastructure.

Potential causes include:

• broadband congestion
• ISP fault
• firewall performance
• switch problem
• failed uplink
• network loop
• backup traffic
• large cloud synchronisation
• overloaded access point
• VPN bottleneck
• malware
• unusual internal traffic

Ask Whether the LAN Is Slow or the Internet Is Slow

This distinction is extremely useful.

Test:

PC → local server

and separately:

PC → internet

If local network transfers remain fast but internet access is slow, investigate:

firewall → router → ISP

If local transfers are also slow, investigate the LAN.

That prevents you blaming the broadband provider for a problem inside your own network.

Use Ping Properly

ping is useful, but don't treat it as a complete network diagnostic.

Try testing progressively.

First:

ping 127.0.0.1

Then your own gateway, for example:

ping 192.168.1.1

Then an external IP:

ping 1.1.1.1

Then a hostname:

ping hgmssp.com

That progression can help separate:

local TCP/IP

from:

local network

from:

internet routing

from:

DNS

But remember that some systems intentionally block ICMP/ping.

A failed ping does not automatically prove the destination is offline.

Traceroute Can Show Where Things Stop

Another useful command is:

tracert hgmssp.com

This shows the path traffic attempts to take.

It can help distinguish problems involving:

• local gateway
• VPN
• ISP routing
• remote networks

Again, don't treat every * * * as a fault.

Routers may deliberately choose not to answer traceroute probes.

Use it as evidence alongside other tests.

Don't Immediately Reset the Entire Network Stack

Microsoft documents commands such as:

netsh winsock reset

and:

netsh int ip reset

for Windows connectivity troubleshooting.

They can be useful.

But I wouldn't begin every investigation by resetting everything.

If the computer has a 169.254 address, investigate DHCP.

If Ethernet negotiated at 100 Mbps, investigate the physical link.

If only names fail, investigate DNS.

Fix the layer that is actually broken.

Network Reset Should Be Near the End

Windows 11 also provides:

Settings > Network & internet > Advanced network settings > Network reset

This removes network adapters and reinstalls them with default settings after restart.

Microsoft explicitly describes Network Reset as a last step after other troubleshooting has failed.

That's because it can also affect:

• VPN clients
• virtual switches
• Hyper-V networking
• custom adapter configuration

Don't use a sledgehammer before you've identified the problem.

Drivers Can Cause Network Problems

If connectivity stopped after:

• Windows Update
• driver update
• docking-station update

check the network adapter.

Open:

Device Manager > Network adapters

Microsoft recommends uninstalling/reinstalling the network-adapter driver when earlier troubleshooting hasn't worked, particularly when connectivity stopped after a recent update.

For business computers, I'd normally prefer the driver supplied or approved by the PC manufacturer before experimenting with unknown driver packages.

The 60-Second Network Diagnosis

Before making any changes, answer these questions:

That table is far more useful than randomly restarting equipment.

A Better Troubleshooting Order

For most network problems, I would use this sequence:

1. Identify who is affected.
2. Determine whether the problem affects Wi-Fi, Ethernet or both.
3. Check whether it affects all internet services or only one.
4. Check the IP configuration with ipconfig.
5. Test the default gateway.
6. Test an external IP address.
7. Test DNS resolution.
8. Check cables, ports, signal and access points.
9. Remove VPN from the test where appropriate.
10. Check network-adapter drivers.
11. Investigate shared switches, firewalls and internet connections when multiple users are affected.
12. Reset TCP/IP or Windows networking only when the evidence justifies it.

That approach gives every test a purpose.

Why Business Networks Need Monitoring

Reactive troubleshooting works when one employee occasionally loses Wi-Fi.

It becomes much less effective when a business depends on:

• Microsoft 365
• VoIP
• cloud applications
• remote working
• VPN
• cloud backups
• servers
• Wi-Fi
• CCTV
• access control

Businesses benefit from knowing things such as:

• whether the internet connection is healthy
• whether switches are overloaded
• whether an access point is down
• whether packet loss is increasing
• whether a WAN connection has failed
• which devices are consuming bandwidth

The ideal time to discover a network problem is before 25 employees open helpdesk tickets.

How Hamilton Group Can Help

Hamilton Group helps businesses diagnose network problems systematically rather than simply rebooting routers and hoping for the best.

We can help with:

• business Wi-Fi
• wired Ethernet networks
• switches and VLANs
• firewalls
• routers
• broadband
• VPNs
• DNS and DHCP
• network monitoring
• Windows 11 connectivity
• network security
• remote and onsite IT support

Whether one laptop cannot obtain an IP address or an entire office is experiencing poor network performance, the objective is the same:

identify exactly where the connection stops working and fix that layer.

Visit or call 0330 043 0069 to discuss business networking and IT support.