As I mentioned previously, I switched over to LLU and ADSL-2+ in February. Since then, I’ve suffered unstable network connections (which has been a pain, to put it mildly) and I’ve been working with ThePhoneCoop’s engineers to try to solve it.
The infernal Belkin was replaced by a modem that The Phone Co-op supplied and they’ve been gradually stepping down the DSL line speed to see if stability improves. According to the router, nothing has been changing though. It’s still been connecting at nearly 7Mbps on a line that used to do only 4.5Mbps on the bundled service, even when it was told to run at a fixed 2Mbps.
The infernal Belkin was still being used as a router and it finally gave up the ghost last week, so I replaced it with a shiny new Netgear DG834GUKv4. As well as being mostly GPL software (notably except the damned Broadcom DSL driver), it gives far more diagnostics. The telling one is that the Signal-to-Noise Ratio was hovering around 6dB. I looked it up on the Kitz information site and my fairly long line (3km-ish) probably isn’t suited to such a low target SNR. I also found a few twitter comments about SNR which reinforced my view. The standard Netgear software doesn’t offer any way to change the target myself: I asked their support service to check and they said it wasn’t offered on “Home” products.
Looking for other solutions to similar problems, I found ADSL: Significance of SNR and attenuation which pointed at The Jesus-firmware for your ADSL modem. One notable benefit of the DGTeam software is that it allows some tweaking of the SNR, as well as having later DSL drivers. I’d like to use OpenWRT, but I’ve not found time to understand the installation and configuration yet, not whether it can work the DSL. I should probably try it on one of the non-DSL wifi routers here first.
After loading the new software and changing the settings, the modem connects at 4.7Mbps with a SNR of around 11 dB. So far, I’ve had one disconnection. I’ll keep the settings under review and see if I can improve things further, then let The Phone Coop’s engineers know what I’ve done.