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Intermittent internet access on ONE PC - Network fine

Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Intermittent internet access on ONE PC - Network fine

Hi
I've noticed something in the last 2 days which is rather annoying me.
I'm getting intermittent internet access on my main PC.
One of my other machines is fine, and VMware computers are also fine. It's just this one irritating machine. The internet just randomly drops dead, and then comes back to life. On the others, it's still alive.
This is really annoying me as the network is FINE. I know this, as I only have one monitor and can therefore ONLY access my other computers via Remote Desktop.
So.. My fileshares accross the network are fine, my other PC's internet is fine (real and virtual), my remote desktop continues working uninterrupted.
Any ideas?
I started to think it might be the network card, but seeing as everything else is fine it can't be.
All ideas appreciated!
I need a new signature... i'm bored of the old one!
9 REPLIES
Community Veteran
Posts: 14,469
Registered: ‎30-07-2007

Re: Intermittent internet access on ONE PC - Network fine

DNS.
When it happens, see if you can access www.plus.net, if not try the IP 212.159.8.137.
Try setting the DNS manually for that system and see if that cures it.
Try any of the following
PN
212.159.6.9
212.159.6.10
212.159.13.49
212.159.13.50
OpenDNS
208.67.220.220
208.67.222.222
Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Re: Intermittent internet access on ONE PC - Network fine

Nope, not DNS. DNS translation is instant and IE shows the IP it's trying to connect to.
Unfortunately, it just takes forever to connect.
When it does, it randomly drops dead and comes back to life etc.
Very weird.
I need a new signature... i'm bored of the old one!
Community Veteran
Posts: 4,729
Registered: ‎04-04-2007

Re: Intermittent internet access on ONE PC - Network fine

Double check the gateway and sub net setting in the network config.
And try a different switch port.
Chilly
Community Veteran
Posts: 14,439
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Registered: ‎01-08-2007

Re: Intermittent internet access on ONE PC - Network fine

Not network settings, I've already checked them (they've been manually assigned by me).
Good idea about the switch port though - I'll try it right after I've hit submit...
I need a new signature... i'm bored of the old one!
Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Re: Intermittent internet access on ONE PC - Network fine

Not sure yet, not had much chance to observe it.
This is a totally unrelated incident to my other intermittent internet problem (where none of the computers could get online).
Right accross every PC, the subnet is:
255.255.255.0
Default gateways are:
192.168.0.1  <== Emergency dialup on old 866MHz
192.168.0.2  <==Broadband
192.168.0.3  <== Spare for any other purpose
All PC's have IPs in the 192.168.0.4-10 range.
I need a new signature... i'm bored of the old one!
VileReynard
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Registered: ‎01-09-2007

Re: Intermittent internet access on ONE PC - Network fine

1. Is this wired or wireless?
2. Have you tried removing 192.168.0.1 and 192.168.0.3 as gateways?

Community Veteran
Posts: 14,439
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Registered: ‎01-08-2007

Re: Intermittent internet access on ONE PC - Network fine

Quote from: James_H
The purpose of a default gateway is to tell your computer where to go to find an address which is outside its own local subnet.

Yep..
Quote
In your case, the subnet indicates that all addresses starting with 192.168.0.xxx are local, anything else has to be found via the default gateway. (Of which you have three defined)

Yep..
Quote
In order to further diagnose your issue, could you define the metric for each gateway?

Automatic Metric
Quote
Also worth adding how the Emergency Dial-up connection is initiated.

Via Windows - Start, Connect To> Show all connections> PlusNet on Portal (With Portal being the machine that hosts the modem - AKA 192.168.0.1)
Quote
I'm also unsure of the purpose of having a third gateway defined as 'unused'

If I'm in an area where a cable broadband is used, or Wifi, then I don't have to reconfigure everything on the network. Simply set the extra device's IP to 192.168.0.3 and chocks away..
Quote
If no device is using that address, TCP/IP requests sent to that address will fail.

Undoubtedly, but then Windows goes through the Default gateway list from top to bottom until it finds one that works. if 192.168.0.1 doesn't work, it shifts down to .2 If that doesn't work .3
Quote
Likewise, if the internet connection on the dial-up box is not connected, TCP/IP traffic sent to that address may fail

And it does fail, but due to this, the next default gateway in the list is used. It works very well all the time on all PCs - Only recently has this one started to become awkward. Might be something to do with that undesirable website the other night..
I should also mention that 192.168.0.1 (when turned on) also has default gateways 127.0.0.1, 192.168.0.2, 192.168.0.3.
Quote
(although it may be forwarded correctly to the DSL router depending on the specific configuration of that box)

Yes, but that would mean the router would (depending on it's configuration) be sucking in packets towards itself. It can't do that. It's down to the sending computer to send them to their destination - router or other PC on the network. The routers config won't make any difference as to where those packets are sent to by the source device.
I'm wondering if it's a virus that has modified something in the registry or something. AVG did delete one last night (also when I moved the network cable to a different port) and so far it hasn't been too bad that I've noticed...
I'll keep an eye on it.
The other computers are totally unaffected by this though...
I need a new signature... i'm bored of the old one!
Community Veteran
Posts: 14,439
Thanks: 728
Fixes: 12
Registered: ‎01-08-2007

Re: Intermittent internet access on ONE PC - Network fine

Well, so far, so good.
Might of been the cable at the switch end. It's on top of a computer under the stairs and in fairness, there are a lot of cables intertwined and probably pulling on each other etc.
I noticed last night one of my machines wouldn't boot when using wol. Had a look at the switch and the light for that NIC wasn't on. Quick wiggle of the wire (after turning it on manually) and the LED came back on.
Looks like that might of been a simple one this time. I'll have to reposition that switch at some point (IT's a sitecom one with magnetci feet so I have to be careful about what part of a computer case it's stuck onto..)
I need a new signature... i'm bored of the old one!
Community Veteran
Posts: 4,729
Registered: ‎04-04-2007

Re: Intermittent internet access on ONE PC - Network fine

Sometimes its the simplest little things that causes the oddest faults.
Chilly