Intermittent Outages

DamnMachine · 02-03-2006, 18:30

Great forum.
I would be really grateful for any opinions on intermittent outages.

I've been an NTL broadband user for about five years, and in general it works just fine, no problems. However on three occasions, the last of which is now, the damn thing has been up and down every five minutes, all day. On the first occasion, an NTL engineer called and fitted an attenuator, which made the problem go away for a while. The second time it got bad, an NTL engineer called and took away the attenuator, which made the problem go away for a while.

But since it's come back again, I guess what I'm asking is whether this is just normal for NTL broadband users, or whether its likely I have some underlying problems with my installation which I need to get to the bottom of.

My configuration:
- NTL 1 Mbit broadband, ntl:home 100 cable modem
- GU16 area
- I normally operate with a Trendnet Wireless router, but I've seen the problem both with and without the router.

What do I mean by an outage?
- you can't ping anywhere outbound of the router from the PC for a period of 1-2 minutes
- in many occasions, the cable modem lights repeat the sequence you normally see after a power-on, suggesting to me that it is rebooting. (NTL support said that my cable modem has rebooted itself 200 times in the last 24 hours)
- after 1-2 minutes, I can ping outbound again and everything operates fine ... until the next time.

Would be very interested in any opinions on this, and what might be causing it:
(a) can signal strength on my cable spur vary over the course of a few months, causing my cable modem to need reconfiguring or something?
(b) can there be something wrong with the cable modem itself? If yes, would switching it for another cure the problem?
(c) can this be caused by running a VPN over the connection?
(d) is it possible the wireless signal from the router could be interfering with the cable modem or with the cable signal in any way?

Many thanks in advance.

\DamnMachine

southwell · 03-03-2006, 08:15

Have they replaced the modem? That would be the next thing i would ask them to do.

I run a wireless router, do VPN and never have any problems.

pjw77uk1 · 03-03-2006, 08:56

So I'm not alone after all!! This scenario, or a variation, has been happening to me for the past four months and gotten a lot worse over the past 3 weeks. Obvious difference is that I'm running off a STB rather than a modem. An engineer is supposed to be calling this morning - the fifth visit in 3 weeks. The last visit, on Wednesday, saw all my kit replaced and still the problem persists! The tech's insist it's a network problem rather than hardware.

DamnMachine · 08-03-2006, 21:15

No, you're not alone.

Yes, the engineer changed the modem for one of the newer 250s.
He was really helpful, and also commented that the signal levels were exactly where they should be.
Since then it has mostly been well behaved, but twice today the connection has gone again for periods. I was able to watch the modem lights quite carefully. Ready goes out and Sync starts flashing fast. The first time it took four power-ons, a call to ntl and on their advice actually unscrewing and refitting the coax cable. The second time it seemed to come back on its own.

The difficulty with progressing this is that it is intermittent and unpredictable, and naturally doesn't happen when an engineer is around. A neighbour six houses down doesn't have these problems, which seems to me to rule out anything on our spur. And if they've replaced the cable modem and it still happens, that would seem to me to isolate the problem to somewhere between my cable modem and the wiring cabinet on the street.

No idea how to get ntl to investigate further, though.

\Damn

Bludger · 09-03-2006, 12:51

Isn't this just the incomatibility problem between the newer cable modems and older routers that only have a 10MBit WAN port?

I had a Motorola Surfboard 4100 modem and after a recent spate of packet loss an engineer came round last week and replaced it with one of the new ntl:250 modems. My old modem was fine with my router but the new one likes to reboot itself every 2 or 3 hours. I did a quick scan of the posts on cable forum and found the reference to the 10MBit WAN port problem.

So, basically, I've had to order a new router. I believe all new routers these days tend to have 100MBit WAN ports but if yours is a few years old it may not have. You can see if it cures the problem by connecting your modem direct to your PC for a day or two and see how many times it reboots (you can see the reboots in the cable modem log). One person found even this didn't help because he had a 10MBit LAN card in his PC. At least that proves the theory anoyway.

Good luck, let us know how you get on. My new router should be arriving today.