I’m in lovely Bangor (Maine) for work, and chose to stay at the Sheraton Four Points hotel and construction zone because it’s near the bus station. Yes, I took the bus, because flying would take just as long for ten times the price and driving wouldn’t have been good for my brand new car (more about that after I get home). One of the features here, as most everywhere nowadays, is free wi-fi via stayhome a.k.a. e-centre. I could browse OK, but I was having trouble with email and ssh tunnels. They’d just lock up. After trying many things to debug the problem, I had sort of concluded that the provider must be blocking traffic, so I googled for their name plus various relevant terms.
It turns out that they’re not blocking intentionally; they’re just screwed up. I pretty quickly found one article on an Eee forum (I’m using an Eee but wasn’t specifically searching for anything related to that) which pointed me to a solution – turn off TCP window scaling. Huh? I know a thing or two about TCP, and I’m still having trouble imagining how e-centre could have screwed things up so that mishandled window scaling affects email but not in web browsing (which is more likely to transfer large amounts of data). Clearly they’re aware of it as a problem affecting users, so why don’t they fix their routers?
Oh well, at least it works now.