How to Solve Windows Network Problems

Locating and diagnosing networking problems can be one of more difficult and frustrating issues that face the computer user. While it’s easy enough to simply restart the computer, thus restarting all the core services, the problem could well be found further along the line. Let’s look at some issues and possible solutions.

The problem with networking problems is the fact that it could be anything from something not loaded correctly when you started Windows up, through to a faulty network interface on your motherboard, or a dodgy cable end that was recently pulled when you last did the hoovering; maybe even an issue with your router, or any switches that lie between you and your access to the internet. Finally, it could be an issue your ISP is having at that time, where everything has slowed to a crawl and for some reason you can’t communicate with an IP address beyond the UK.

There are a vast number of reasons as to why you’re having a network problem. So with that in mind we’ll have a brief look at some of the diagnosis techniques and tools, commands and connections, tips and troubleshooting that can all combine to give you the user an intense, networking headache.

Simple scenarios

Let’s assume that you’ve powered up your PC and clicked on IE, Firefox, Chrome or whatever else that allows you to browse the internet, and instead of their being your usual home page, you’re left with as blank screen.

Naturally you try another page, maybe even another search engine, but within seconds you come to the conclusion that your internet connection is down. The same can also be said for accessing any internal network resources, such as loading something off a NAS box, or connecting to a wireless printer, for example.

Either way, something untoward is going on, and it can be as simple as a knocked cable or as complex as your Hosts file being corrupted, or a hardware issue.

Visual checks

The first thing to do of course is make a quick visual check. If you can connect to your home network via a switch, or a PowerLine adapter, and it’s in easy reach of where you are, then take a glance at it and make sure that all the visible LEDs are green and functioning accordingly. Red LEDs usually indicate a loss of connection on network hardware, or no lights at all can indicate a loss of a connection, so take a moment to just double check the status of the device.

If it’s a PowerLine adapter, then these things have a habit of stopping due to losing communications with its paired device. In that case, you can usually remedy the situation by unplugging it, waiting a few seconds and plugging it back in again. Simple stuff, but it works.

If you’re connected to a switch, then have a look and make sure it’s powered up and that the connection to your PC is in the relevant network port securely, as is the connection that goes off to the router, downstairs, or whatever.

If everything from the PC looks okay, then the issue could lie further down the cable – unless an LED is informing you otherwise – so you can quickly take a look at the other end of the cable, or unplug the other Power Line adapter. Also, check the ends of the network cable for any signs of wear and tear or damage. If the end of the cable is dangling by the last few threads of the cable inside, then it’s obvious the time to replace it has come. If the cable looks okay, but the lights on either end of the switch/router say otherwise, and if this is a common issue with your setup, then it could be time to invest in a cable tester to check the integrity of the cable. If it’s faulty, then at least you’ll know and you can arrange a replacement.

Finally, check the network device you’re trying to communicate with, router, NAS or printer, and see if everything is looking okay with it, and that it’s actually powered up. Nine times out of ten, a network problem can be easily resolved simply by looking at the connections and checking they haven’t been intentionally (children, cats etc.) or unintentionally (hoovering, turning the power off at the switch) meddled with.

The visual checks may sound time consuming, but in reality they can be run through very quickly, and if you know your home network then you’ve usually got a pretty good idea of where a potential problem may lie.

Windows checks

If everything physical seems okay through the visual checks, the network connection issue may well be something to do with your PC.

If the problem occurred from the moment you started the PC then it could have something to do with the key essential networking services not loading, or starting, correctly. This doesn’t happen too often, but it does happen, and the best remedy is to laughably restart your PC. You could check the state of the network services by pressing the Windows key and ‘R’, then typing services.msc and pressing enter. This will launch the Services window where you can see what’s started and what hasn’t. Generally speaking, starting the services yourself is perfectly fine but there’s usually something else that needs starting beforehand, or afterwards and the whole thing gets messy or doesn’t work quite as well as it should. So it’s often best to let Windows sort it out with a quick reboot.

The next best check is the condition of the PCs IP address, default gateway and subnet. To do this enter the command prompt (Windows key and ‘R’, enter cmd into the box and hit enter), and type:

ipconfig /all

This will detail the connections you have on your machine, either physical or virtual, and list their respective IP addresses and if they’re looking at the correct router or not.

ipconfig

Things to look out for here include the Default Gateway – usually your router; DNS Servers – how your PC translates addresses to names, and the IP Address – the home network address of your PC.

If the Default Gateway looks wrong, i.e. it’s looking at 0.0.0.0 then your PC isn’t getting anything from your router. Likewise, the DNS Servers could be down and not responding so you won’t be able to translate 151.101.0.81 to the BBC website. And the IP Address of the PC could be 169.254.0.0, which is the Link Local Block allocated between hosts on a single link, the default IP address as dished out when the PC can’t see a local network.

The best option here is to check that the router is up and running, and that you haven’t installed any other DHCP server recently, like a NAS device or other router. Also check that your PC isn’t using a manual IP setup, set it back to DHCP to pick up the router.

If all else fails, you could reset the IP configuration data of the PC by entering the following:

ipconfig /release

To release the name specific data (not always needed, but useful to try). Then:

ipconfig /renew

This command should renew the address lease from the DHCP server (your router) and refresh everything. You can then check with an ipconfig /all again to see if this have alleviated the issue.

Should you suspect your PC has become infected with some kind of malware, and is being used as a connection to send and receive data without your knowledge, which can greatly affect the network, you can check for TCP and UDP port usage, along with the Process ID of the program by entering:

netstat –nao

This rather complex list will detail the incoming and outgoing active connections for your PC, and in particular what programs or system services are using them. Careful checking of the PIDs will reveal a suspect program should one exist.

netstat

If you also suspect that the ISP’s DNS Servers are at fault, either by being slow, bombarded by an outside source, or just plain wrong, then you could try and Pathping a known external address to see where the problem lies. For example, the following will Pathping the BBC:

pathping bbc.co.uk

Should the issue lie beyond your router, then there’s not a lot you can do about it, other than try and locate another DNS server and enter that manually into the PCs networking setup. Also, you could Pathping your own internal router, to see if there’s anything at fault somewhere along the line. Generally this won’t reveal much unless you’re attached to a big corporate network, but it’s often worth a look.

Finally, to add to the built-in list of tools, sometimes the most simple are some of the most effective. By this we mean the Windows Network and Internet Troubleshooting Wizards. Surprising as this may sound, the Network and Internet Troubleshooting Wizard can go some way to analysing your current network connection and seeing if there’s anything untoward going on with it.

In addition to the basic ping test and connection integrity, which is all it’s really doing in the background, you can troubleshoot any issues you may be having with the state of the Windows Firewall, which in the past has been known to go a little off-key and block all incoming connections.

However, for the vast majority of us, the built in Windows command prompt tools are more than enough to identify an issue in our home network.

Third party tools

There are times though that the built-in commands of Windows: Tracert, Ping, Pathping, Nslookup, Netstat and so on, simply won’t reveal the kind of detail you need to get into to help pinpoint a certain network problem.

Most of the time, a common network issue can be resolved through the built-in commands, but if you have a potential issue with malware, several routers, rogue packets or just something you can’t put your finger on but you know exists, then you’ll need to delve deeper to find the elusive and use one of the many third party tools available.

When we say many tools available, we mean it. There are hundreds, probably thousands, of tools and programs that can be run to determine the exact nature of your network. There are some old classics that still work today: Ethereal (now called Wireshark), Mapnet, View2000, Netmeter, LANExplorer and Alchemy Network Monitor are just a few of the programs and tools that can be found and will reveal a lot more about the packets, traffic and overall effectiveness of the network your PC is attached to. The trick of course, is finding out which will work the best for you.

One of the best all-round network scanners and analysers is the former Ethereal, or Wireshark as it’s known as these days. The latest version, V3.2.1, is available via the Wireshark page at wireshark.org, but it does ask for the installation of Npcap or WinPcap, which is the Windows version of the Libpcap library driver to capture packets. It’s not essential to install Npcap, but it can make for a better all-round network diagnosis if you do. The only reason we’re mentioning this is because some anti-malware clients regard Npcap as an infection of some kind, and it used to have a bad press among users some time ago. It’s up to you, but you can get away without it being installed.

Wireshark will provide you with a graphical representation of what’s going on inside your network. It’s a packet analyser that captures the packets on the network and returns as much detail as possible regarding those packets. With it you can troubleshoot network problems, examine any security flaws and learn a lot about the internal network protocols, and what’s happening to all those 1’s and 0’s inside the cable. It’s use a little too complicated and long winded to get into here, but suffice to say it’s relatively easy and there’s a handy How To included with the program.

Wireshark

NetVision, or Axence NVision as it’s known as now, is another old school network analyser that’s been brought up to date for modern networks and users. Along with its sibling kit of useful tools, NetTools, all of which are available from axence.net, NVision is an all-powerful set of network management programs combined into a single suite. With it you can gain graphical reports of all the connected clients, nodes, devices, switches, routers and so on. The software will analyse the type of connection, speed and whether or not it’s degrading over time; you can see the response times of other computers and devices on the network, as well as any services you have installed such as POP3, HTTP, FTP or SMTP. And you can measure and track the services and networking useage of every machine connected to your network, including the ability to remotely connect or terminate a connection should something happen.

It is indeed a powerful tool, probably a little too powerful for the average home user admittedly. Still, you now know of its existence and should the need ever arise, you can have it installed, scanning and analysing your network for problems or potential problems in no time.

Firewalls

The Windows Firewall can go a little heavy on the rules sometimes. Usually it’s no fault of its own, a game being installed that requires registration from an external server, a program that needs to get through to check for updates, even browser updates frequently chop and change the rules around in the Firewall without you even knowing. Therefore it’s a good idea to check the rules on your Windows Firewall should something be letting traffic through that shouldn’t be there, or it’s failed spectacularly and stopped all communications.

firewall

You can open the Firewall via the System and Security section in the Control Panel, however, an often easier way to read the rules is via a Notepad pipe from the command line. Enter the following in to an Administrator level command prompt (click on the Start button, type cmd, when it appears in the list right-click and choose ‘Run as Administrator’):

netsh advfirewall firewall show rule name=all > firewallrule.txt

This will dump all the necessary details of the Windows Firewall into a handy text file. Next, enter:

notepad firewallrules.txt

To open the text file in Notepad. You can then browse through them and see if there’s out of place, closed or just plain wrong.

Keep it simple

One of the easiest rules to remember though when you’re checking for network issues, and one that you’ll kick yourself later for not doing, is to keep the design of your home network as simple as humanly possible.

We’ve seen so many over complicated home networks grind to a halt and the poor maintainer of the network is then left to fathom out which of the wireless extenders, mini switches, extended routers or Power Line adapters is at fault. So do yourself a favour, if you can, keep the network as lean as possible and as easy to maintain as possible. That way, when a network error does occur, you’ll be able to nail down the culprit in no time.

David Hayward

David has spent most of his life tinkering with technology, from the ZX Spectrum, getting his hands on a Fujitsu VPP5000/100 supercomputer, and coding on an overheating Raspberry Pi. He's written for the likes of Micro Mart, Den of Geek, and countless retro sites and publications, covering reviews, creating code and bench testing the latest tech. He also has a huge collection of cables.

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