Yesterday something went a bit weird with my parents DSL.. it was working all right up until then. Apparently around 4:30pm, the router lost its connection and then reconnected. My dad told me there were a few BT vans in the street so I’m not sure if they were messing with DSLAMs in the green boxes something like that.
Anyway, what happened after the reset had me a bit stumped until this morning when I realised what was happening. The symptoms of the problem were that basically only a few random websites were working.. Google happened to be one of them and a handful of others. The others would sit on ‘loading’ but never actually load the page. MSN messenger wouldn’t work. SSH would work until a certain number of characters had been transferred… that was what made me think of MTU..
So I managed to view a few sites about Tiscali MTU via Google Cache. They all said Tiscali’s recommened MTU was 1500, however that’s what the routers WAN interface was already set to. I Googled a bit more and found BT’s DSL recommended MTU was 1458… 10 seconds later I’d changed the Speedtouch 510v4 to use this value and everything worked!
So there you go, 15 hours of downtime because of some shitty MTU problem! Hope this solves the issue if anybody else encounters such a weird problem!