Curious line behaviour between 5:30pm and 6pm (6th and 7th Jan 2011)

[#1]

I was online this afternoon until 5pm then had to go out and shut down the PC (but obviously not the router) and then booted it back up again at 5:30pm when I got back. (Ok I could have left the PC on for the duration but I wasn't sure how long I would be gone so that is largely irrelevant).
Up to 5pm everything was fine but at 5:30pm it was as though I had been temporarily switched to a dial up connection as pages either loaded excruciatingly slowly, or incompletely or not at all. I couldn't acces my emails either and the situation was the same in both IE8 and Firefox 3.6.13. Curiously it was exactly the same situation at the same time yesterday evening, having been ok before and after, and indeed it is perfectly ok again now. I didn't lose my DSL connection at all throughout, although I did break the Internet link just in case I had acquired a heavily contended IP address, but this had no effect on the problem. I had been on a 91 prefix IP (up to 5:40pm) and switched to an 87 prefix one which is the one I am still on now.
Having resolved the various problems that I experienced last autumn my router has been directly connected to the test socket since early December. Since then the download sync has ranged from 14691kbps on 10th December down to 12150kbps on 26th December and is now slowly creeping back up again with a current figure of 13057kbps after an automatic disconnection at around 10:20am this morning. Actual download speeds whilst on the 14000kbps+ sync were between 10000 and 11000kbps (and occasionally marginally higher) whereas now it is 9329kbps down & 373kbps up which ties in with the reduction of IP profile from 12000 up to Christmas as against 10000 now. It was nice to be on a 14000+kbps sync but the difference between that and the current level is only marginally different and only really noticeable on large downloads.
What I am more concerned about is these periods of effective unusability as it would have been all the same if I had been using online banking or buying something online instead of playing a Facebook hosted game. <too-much-free-time smiley> I have only noticed this problem in the last couple of days so it seems unlikely that it is down to general evening server load so I wondered if it was related to maintenance work at the exchange or something along those lines. If so, and if I know that it will be happening again I can just avoid the times in question.
Just in case it is relevant, these are my current router stats running, as I said above, from around 10:20am today....
Link Information

Uptime: 0 days, 9:50:51
DSL Type: G.992.5 annex A
Bandwidth (Up/Down) [kbps/kbps]: 440 / 13,057
Data Transferred (Sent/Received) [kB/kB]: 0.00 / 0.00
Output Power (Up/Down) [dBm]: 12.5 / 0.0
Line Attenuation (Up/Down) [dB]: 14.0 / 28.0
SN Margin (Up/Down) [dB]: 30.0 / 8.0
Vendor ID (Local/Remote): TMMB / IFTN
Loss of Framing (Local/Remote): 12 / 0
Loss of Signal (Local/Remote): 1 / 0
Loss of Power (Local/Remote): 0 / 0
Loss of Link (Remote): 0
Error Seconds (Local/Remote): 28 / 0
FEC Errors (Up/Down): 0 / 245,464
CRC Errors (Up/Down): 0 / 1,152
HEC Errors (Up/Down): 0 / 1,105
I don't consider this issue severe enough to raise a support ticket but all the same I would be interested to know if there is a logical explanation.
Thanks.
Spruance

[#2]

What does it say for your exchange status here http://usertools.plus.net/exchanges/

[#3]

Nothing much of any value....
Code: EMBOSTO
County: Lincolnshire
Enabled: 30 Aug 2001
Market: 1
Virtual paths: Green
There are currently no known capacity problems on your exchange. There may still be an exchange problem, however BT are not currently reporting that they are aware of it. Please contact Support if you are having speed problems, who can advise further.
Record last updated: 24 Dec 10
It is just strange that it happened two days running at the same time, and come to that it is only 25 minutes away from zero hour now, so the PC is staying firmly on whilst I hope for the best.

[#4]

Yep, that looks OK , VP Capacity is Green so that shouldn't be the cause of the slowdowns.

[#5]

Well it didn't happen this evening so if that's the end of it I'll have to put it down as one of life's great mysteries.
Thanks for your interest MisterW.

[#6]

Just by way of a postscript, this issue has recurred twice more. Once around Sunday lunchtime and again around the 5:30pm mark on Sunday both times for half an hour and without loss of DSL connection and the common denominator again is graphics heavy game pages on Facebook. Having said that I currently have 10 tabs open in two browsers, plus my photo editing software and a Word document and everything is working perfectly (as indeed it should) also my IP profile has risen to 11,000kbps so I am back in 10,000kbps download heaven!
I just wondered if these occasional glitches might be in some way connected to the signal strength of my Thomson TG 585 v7 wireless router, which usually ranges between fair and moderate, it being a G-rated router whereas my wireless adaptor can receive N-signals from a suitably configured device, and thus maybe I should invest in an N series router? I was thinking about getting a new router anyway as I am a little vulnerable with just the one and it would be a good idea to have a spare - just in case.
Any thoughts on the signal strength theory?
Spruance

[#7]

Could this problem be the same as the one reported here?
http://community.plus.net/forum/index.php/topic,92223.0.html

[#8]

Thanks for the link snozboz, and yes it does seem similar but I have no problems the rest of the time and I visit YouTube quite frequently. Yesterday I was streaming a New Zealand radio station all eveing and it worked perfectly. That's what I find so odd, as most of the time it is working perfectly.
I think I will still try to get a back up router though.
I tend to spend more time online than watching TV yet there are three working TVs in the house and two spares in reserve in the loft but I have only the one router!