Strange Networking Issue

[Cringer]

Not directly Progress related but if any of you gurus can help I'd be much obliged.
I have a Win10 PC connected to my network via a wire in a Gigabit NetGear switch. Once it's booted up I lose internet connectivity on all devices connected to my router whether they're wired or wireless. If I disconnect the cable from the switch for this particular PC then everything works fine.
Any ideas what I can do to troubleshoot this?

 

[Rob Fitzpatrick]

So does the picture look like this?

  -------: wired connection
  =======: wireless connection


  Win10 PC ----------- NetGear switch ----- WiFi router with integrated switch ---- internet
                             |                          |
  other wired devices -------+                          |
                                                        |
  WiFi devices =========================================+

• Are there any enabled UPnP features in the switch or router?
• Do the other devices get their IP address statically or via DHCP?
• Do the other devices get their DNS server info statically or via DHCP?

What is the state of affairs when your other devices "lose internet connectivity"? Specifically:

• Does the router still have an IP address from the ISP?
• Do the connected devices have a valid (i.e. non-auto-config) IP address and DNS server settings?
• Can one of the other devices ping an internet address that normally responds to ping requests, like the Google DNS server (8.8.8.8)?

 

[Cringer]

Thanks Rob. Your picture is spot on.

• The switch is a Netgear GS108 device that as far as I know has no way of configuring it. It's just plug and play.
• The Router has UPnP enabled evidently.
• The devices are allocated their IP via DHCP
• DNS Mode on the router is set to obtain it automatically

When I lose connectivity:

• Yes the router is still fine - the ISP can see the router and can connect to it
• Yes the devices seem to still have an IP
• None of the devices can ping 8.8.8.8 reliably. It pops in and out of responding. Interestingly at the moment it is just really slow responding rather than not responding at all.

You'll have to go easy on me - networking really isn't my strong point!

 

[Cringer]

Interestingly, and this could just be a coincidence of course, when I plug the Ethernet cable in for the Win1o device into the switch, all the lights go crazy. As soon as I unplug it they go quiet.
Will try changing the cable. Can't be as simple as that surely?!

 

[Cringer]

Nope it's not the cable.

 

[Rob Fitzpatrick]

Sounds like the symptoms of a routing loop, though with a straightforward setup like that I can't explain how that could happen.

It's also possible that the Win10 box is infected with malware that is flooding the LAN segment as soon as it connects.

When this happens, what do you see on the Win10 box itself? (e.g. in Resource Monitor, Task Manager, Process Explorer, Wireshark, etc.)

 

[Cringer]

Good question - I'll check that out.

 

[Cringer]

Thanks for the help Rob. There was no Malware. Phew. Wireshark was a good tip though - established I had a LOT of communication with a particular IP address. I did a whois and it was Microsoft's. Upon further investigation, OneDrive was trying to upload a load of files. No idea why because I've not added files to OneDrive on this machine for ages. Anyway, shutting down OneDrive seemed to fix the problem so I've reset OneDrive and we'll see what happens.

 

[Rob Fitzpatrick]

Good to hear!

 

[Cecil]

Can you turn off 'network discovery'.

Control Panel> Network and Internet > Network and Sharing Center > Advanced sharing settings

 

[Cringer]

Can you turn off 'network discovery'.

What benefit will that give me Cecil?

 

[Cecil]

What benefit will that give me Cecil?

Not sure, apart from your computer constantly broadcasting it's self as a media server or something like. It's just when you said that when you plugged in the network cable that your activity LED is rapidly flicking, I remember that reading about Windows 10 and the 'network discovery' was a real problem.

 

[Cringer]

Ah ok thanks Cecil. I'll see what happens when I disable it.