belkin F5D8633-4 line sync problem on adsl2+

jonph · 10 Feb 2010 at 18:15

hi folks,
having a problem when switching on router.when switching on,line syncs but takes several minutes to connect to isp.After about 5 mins sync is lost. it re syncs straight away but takes ages to reconnect to isp. this can keep recurring for half an hour or so which is a real pain.
I'm guessing the modem is trying to sync at too high a speed and keeps dropping out untill it settles.I spoke to my providers(ukfsn)and they said to set the modulation on router to G.DMT to try and establish if it's a line or router fault.Problem is, there doesn't seem to be an option anywhere in the router settings to change modulation type.I've been on llu service since december and when the sync rate is stable I've had varying connection speeds between 3000kb and 4500kb.
my present stats are:
data rate:3646down 979up
noise margin:9 down 6 up
atten:60 down 27 up
I'm not expecting ridiculous speeds with my stats, but it would be nice to switch on an use the net without having to wait half an hour + before its usable.
can anyone advise if modulation can be changed on this router(contacted belkin support but total waste of time), or if there are any settings I can change to to stablise things?The router is supposed to be adsl2+ compatible, can anyone confirm this or has anyone had issues with this router and adsl2+ ?
I have done all the usual checks,plug into master socket, swap filters etc.
the only thing I have'nt tried is a different router.
many thanks in advance

jonph · 11 Feb 2010 at 21:55

anyone?

tolien · 11 Feb 2010 at 22:25

Have you tried another modem?

jonph · 11 Feb 2010 at 23:31

not tried another modem yet.trying to borrow one as I don't wannt to fork out untill I'm sure of the problem.
belkin support have finally replied. they say the router is adsl2+ compatible and the the modulation can't be changed.they said to set the mtu to 1400 which I have tried, but does'nt seem to have helped. ukfsn say the mtu should be 1492. not really sure what the mtu does exactly but thought this should be set higher rather than lower?

jonph · 19 Feb 2010 at 20:35

ok.tried a different modem(netgear dm111p) line sync is now stable.
stats:
line rate:down 3388kb up 1023kb
attainable line rate: down 3752kb up 1040kb
noise margin: 10.8db down 6.2db up
attenuation:51.5 down 28 up
I had a stable line at 4200kb yesterday
now although I seem to have stable line sync,my internet seems pretty slow.web pages seem slugish loading and downloads from usenet (easynews)are useless(dialup speeds) my isp recomend to set mtu to 1492 which is what I have. I've tried downloadig file from various sites and the speeds are pretty slow. Any suggestions anyone?
also can anyone explain why my attainable line and actual line rates are different?

jonph · 20 Feb 2010 at 18:25

anyone?

tolien · 20 Feb 2010 at 19:09

If your sync rate's been all over the place, it's possible you have a reduced IP profile (assuming your ISP uses BT Wholesale) or maybe it's packet loss. It could be loads of things, and Usenet and "various sites" aren't a particularly good test.

jonph said:
also can anyone explain why my attainable line and actual line rates are different?

"Attainable line rate" would be what you'd get at a 0dB SNR margin, if it stayed in sync long enough. Your downstream SNR margin's a bit over default as well.

jonph · 20 Feb 2010 at 19:30

thanks tolien.
the line is c&w llu.
when I was on adsl(with same provider, ukfsn) my usenet would download most of the time at about 2000kb. I ran a traceroute to easynews and it did'nt show any packet loss although the speed was only about 50kb.ukfsn's tech phone support seems to be only available during buisness hours(9 to5) which is when I'm at work and makes it difficult to contact them and emailing them can take a few days to get a response.I've tried playing with a few settings on the modem but am I right in thinking that each time I change something and reboot the modem it will show at the exchange as sync loss and reconect at a lower speed to try and stabelise the line?If I just leave the modem connected for a few days will the line sync get slowly raised to find a maximum stable rate or do I need to contact my isp to reset the line?

jonph · 21 Feb 2010 at 23:50

well heres another strange thing.Because of my line sync problems, all I've had connected to my phone line for the last few days is my modem and the line has been stable but web pages seemed slow to load. today I plugged the phone back in and although my line sync speed has slowed slightly web pages are loading better and my usenet connection is back to normal! I'd have thout with the phone unplugged there would be less chance of line problems.