Is my router failing?

Last year I was consistently achieving download speeds of 3Mbps, recently it has been about 1Mbps.
I have a Zyxel P-660HW-T v2 802.11g Wireless ADSL 2+ 4-port Gateway which I purchased a few years ago. It is connected to an extension socket which is about 1 metre from the BT socket, (a very old style one installed over 15 years ago). There have been few problems with my connection speed until a few weeks ago when I have sometimes only been able to achieve dial-up modem speeds.
I never use a wireless connection, preferring to connect to my computer using an Ethernet cable, and our 2 phones and the router are all connected via filters.
After several days getting 1Mbps at different times of day I decided to plug the router into the BT socket, disconnecting our 2 telephones and the speed immediately increased to about 2Mbps. Reconnecting the 2 phones made no change to the download speed. When I moved the router back to where it is normally plugged in the speed stayed at about 2Mbps.
I was stil achieving this speed five hours later, at 2300 hours. When I tested it the following day the speed had dropped to 1.5Mbps throughout the day, but I decided to switch the router off and on again and the speed increased to 2Mbps.
Possibly the speed increase I experienced when moving the router to the main BT socket was due to the router being switched off and on again, so I will have to try that again when the speed has dropped, (if it does). However I am still no nearer getting back to the 3Mbps I used to receive.
The router feels quite warm after it has been on for some time, but I cannot remember if this was the case when it was new.
Is it possible that the router is failing and causing the speed to drop off with time?
If so, then what router should I go for? Ideally I just want one that is 'plug and play' and which I can connect to my computer via an Ethernet cable, and does not cost a fortune.
Any help appreciated as I am getting frustrated with my poor connection.
Viv
PS my ISP is Tiscali (now taken over by Talk Talk).

Please post your router stats, see http://kitz.co.uk/adsl/frogstats.php

Are these the stats you asked for?
System up Time: 0:12:17
CPU Load: 6.53%

WAN Port Statistics:
Link Status: Up
Upstream Speed: 537 kbps
Downstream Speed: 1704 kbps
Node-Link Status TxPkts RxPkts Errors Tx B/s Rx B/s Up Time
1-PPPoA Up 1351 1671 0 0 0 0:02:14


LAN Port Statistics:
Interface: Status TxPkts RxPkts Collisions
Ethernet Up 1576 2507 0
Wireless 54M 291 0 0

noise margin upstream: 17 db
output power downstream: 12 db
attenuation upstream: 28 db
carrier load: number of bits per symbol(tone)
tone 0- 31: 00 00 00 34 56 77 88 88 99 89 88 88 87 66 54 32
tone 32- 63: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 64- 95: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 96-127: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 128-159: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 160-191: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 192-223: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 224-255: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 256-287: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 288-319: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 320-351: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 352-383: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 384-415: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 416-447: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 448-479: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 480-511: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

noise margin downstream: 15 db
output power upstream: 17 db
attenuation downstream: 45 db
carrier load: number of bits per symbol(tone)
tone 0- 31: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 32- 63: 00 00 00 00 00 00 00 16 66 66 66 65 55 55 55 55
tone 64- 95: 55 55 55 50 55 55 55 66 66 66 66 66 77 77 77 77
tone 96-127: 78 78 78 77 77 77 77 76 55 55 54 44 56 62 64 52
tone 128-159: 24 55 55 24 24 44 04 24 04 02 01 22 00 00 00 00
tone 160-191: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 192-223: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 224-255: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 256-287: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 288-319: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 320-351: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 352-383: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 384-415: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 416-447: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 448-479: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
tone 480-511: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

Viv

I have found some stats from last year for comparison, in case it helps :-
Date 10/11/10 12/04/11
Time 12:00 23:15
Upstream noise margin 18 17
Output power downstream 12 12
Attenuation upstream 27 28

Downstream noise margin 5 15
Output power upstream 18 17
Attenuation downstream 46 45

Upstream speed Mbs 0.448 0.537
Downstream speed Mbps 2.720 1.704

I note that the downstream noise margin has jumped from 5dB to 15 dB while the other figures are virtually the same as six months ago.

I tried to get the figures to line up but that disappears when previewed. I hope it is understandable.
Viv

I have also noticed that the carrier load: number of bits per symbol(tone) for upstream has remained constant over the last 6 months spanning 6 to 31, but the downstream figure now only spans 46 to 151, whereas last year it used to be 34 to 159. I have no idea if this information is relevant.
We have been experiencing some noise on the line when making or receiving phone calls so this may be part, or all, of the problem.
Viv

We have been experiencing some noise on the line when making or receiving phone calls so this may be part, or all, of the problem

audible noise on line - get this fixed first. that should get the noise margin back to a better level.
but I also suspect the line has been moved from adsl to adsl2+

Thanks for the suggestion. I will contact BT about the noise. It looks as if the router can handle ADSL2+, so if the line has been moved from ADSL should this have caused a problem?
Viv

I used BT's online problem checker for noise and it decided that there was no problem. I also decided to check the router stats after plugging it into BT's master socket and disconnecting all phones. There was no noticeable difference (1dB max) in upstream/downstream noise margin, output power or attenuation.
Viv

have you tried (just) a phone into the test socket?

if there is /any/ noise there then fix that first

also routers can fail, and put noise on the audio side

Yes, I did try two phones in the test socket, (not both at the same time), I could not detect noise with either.
Viv

That carrier load table shows the tones/frequencies that are being used
by your router. The more frequencies used, the greater the bandwidth.
You are currently only using a little over half the available frequencies for
an ordinary ADSL line or about a third of those available if your exchange
is enabled for ADSL2+. I reckon that, if the noise/interference on your
line is sorted out, you ought to get easily more than 3Mbps.

Also, the attenuation for your line is not ridiculously high. The Max speed
calculator on the Kitz site (Linkie) even suggests that you might get as high
as 5 or 6 Mbps.

Have you ruled out the possibility that the noise might be coming from your
internal extensions. Did you test in a master socket where you can isolate
the house extensions from the incoming line completely (NTE5) ?

- Alex

Edited by deleted (Wed 13-Apr-11 19:26:05)

Both Talk Talk and BT suggest that my phone number should have a max speed of about 3Mbps, which I used to be able to achieve.

Yes, I have tried plugging the router into the BT master socket with no phones, or anything else, connected and using a long Ethernet cable to connect to my computer.

There seems to be almost no difference in the router stats whether it is plugged into the master socket with nothing else connected and my normal setup with the router plugged into an extension socket which is about 1 metre from the master socket and two phones connected.

Viv