Ethernet broken but WiFi working - please help

[#1]

What happens if the router input is disconnected from the ADSL filter and you plug a computer into a LAN port, does the LAN light still go out? Or alternatively disconnect the router input from the ADSL filter with a computer connected - in this case does the LAN light come on?

For the technical watchers I'm wondering whether there could be a high common mode voltage on the ADSL signal coming into the property that is incompatible with the LAN port. This would not affect the wireless performance. If this was the case it would be a BT problem.

[#2]

Thanks again Hairy MkBiker,

you're probably right, but I'm a bit bewildered that both pcs should have the same problem at the same time.

Still, I'm going to use my pc wirelessly right now as I need to catch up on a few things, and then I will do as you suggest and hopefully find the cause by trial and elimination.

[#3]

Baldrick, thanks,

I disconnected the input from the filter, connected ethernet cable to pc, and the link light remained green.

I then connected the input cable, and the light remained green.

[#4]

Things that go bump in the night! The problem will come if it recurrs and keeps dropping the connection. Convincing BTOR that it's their problem could be an issue.

[#5]

I think I must have misunderstood your question or used wrong terminology, my apologies. By 'link light' I meant the light confirming that the Ethernet cable is connected, but regardless of that the internet lights remain unlit or extinguish whenever a pc is connected by wire

I am still confined to wireless only at the moment and I am at a loss as to why my wired connection has gone.

[#6]

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@kmw350 wrote:

, and with two different routers (Thomson TG582 & 585 models).

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As both routers are the same make, did you also swap their PSUs?

If you did, have you tried powering the router from a different mains socket (not the other on a double) just in case its a power issue.If both PC's are plugged into adjacent mains sockets, it might be worth trying others.

[#7]

Yes, I used their own PSUs each time, but I have not yet physically moved the PCs to different power outlets, so I will be trying that soon.

I did already try different power points for the routers though.

[#8]

I think what you are saying is that if you disconnect from the filter and connect the router to a pc the ethernet light comes on correctly and stays on but when you then connect to the filter the ethernet light stays on but you get no dsl light. On th other hand if you connect to the ethernet first then plug in to a pc neither the ethernet or dsl light come on. 

This is still suggesting to me that there is a common mode voltage present between the adsl signal coming into the property and the pc ethernet port, which is in excess of what the router can stand. I note that both your routers are thomson units. If you could borrow one from another manufacturer that might fix it. 

My gut feeling that this is a BT problem but whether you will get them to accept that will be the problem. The risk is that they will plug in their tester, which may not show the problem then try to charge you for the call out.

[#9]

I'm not sure I can borrow one, but I'm willing to buy a new one if a different manufacturer model might fix it. How about a TP Link AC750, is that worth a try?

(Looking on the positive side, even if it didn't fix it, it should be an upgrade in terms of wireless signal throughout the house).

[#10]

Before you spend lots of money or report a fault it is worth persevering for a bit longer. Can you borrow a laptop and try that with no mains charger connected? If my theory is correct then this will work on the ethernet port. Also it is possible that you may have an earth fault either on the socket you are using for the PC, the house circuit or indeed the house supply. I don't suppose you have a test plug - this sort of thing: http://www.screwfix.com/p/lap-ms6860d-socket-tester/91596? At £7.57 it's worth having one anyway to check all your sockets are safe.  

[#11]

I've missed something, somewhere. There are two PCs and a router connected to two mains sockets. So, there is something else in play (eg a 4-way strip). If so, what happens without the strip in place (as you only need the router and one base unit connected to the supply for a test)?

Phil

[#12]

I'll get a test plug this afternoon, borrow a laptop & try that via Ethernet; & I'll remove the 4 x way extension & plug the pc & router straight in to the sockets, and report back, it might be a day or so depending on when I get chance.

Many thanks for all the help and suggestions.

[#13]

Well,

the test plug is a very useful item, and I'm pleased to say it shows everything ok in all my sockets through the house.

I was unable to test with the laptop I borrowed as when I got it home I found it didn't have the correct socket!

But in any case, there has been a development - I noticed that my speeds had gone back up to around 8Mbps (it was down around 3Mbs the day before), so I plugged the Ethernet cables back in just to test, and lo and behold, they are now working again!

I've updated the support ticket to that effect but I'm still waiting to hear from PlusNet as to whether it's because they found the fault or it just somehow righted itself.

Hopefully that will be the end of the problem & the speeds will settle back up to 10 in the next day or so.

Fingers crossed, and thanks again to all of you for the sound advice and suggestions, and to PlusNet for their help when I phoned & for anything they may have done to get it working 

[#14]

Good news that it's fixed and you find the test plug useful. Based on what you are saying I suspect that this was a problem in the telephone exchange that has been fixed. As such it will be outside of the bounds of PN responsibility. Hopefully it has been fixed and it's not an intermittent fault that will come back. The slow data rate will be due to the high number of disconnects caused by you plugging in the Ethernet cable. This could take ages to correct if left to it's own devices. However if you ask PN nicely if they will reset the SNR as you have had a fault that is now fixed, that will result in an immediate improvement.

If you a lucky one of the PN staffers will see this and do it for you. 

[#15]

Just to mention different mains sockets, common mode voltages etc won't be a problem as Ethernet ports are fully transformer isolated so no common mode current can flow from one device to another via it's Ethernet connection.  The same is true of telephone circuits, ADSL is fully transformer isolated at the customer premises (inside your modem) so no current can flow between the telephone line and any other port or power connection of your modem.  I hope your problem stays gone!!