It also depends on what software you are running, if you run Bit Torrent/ utorrent, then it doesn't seem to recover when the router goes down.
I had the same problem and i THINK it was due to my Dlink router, or the DSL modem provided by TOT - I replaced it with an all in one Belkin N150 and this thing flies.
For some reason, if the modem router went down using uTorrent, the only way to get the thing going again was to close uTorrent and restart - obviously not an option in the middle of the night, unless you have a Burmese maid or something.

VUZE, on the other hand seems to recover itself much better after the modem goes down in fact in about 2 minutes it is streaming away merrily.

You should try and limit your connections, I found it best to limit maximum connections to between 50-100, maximum upload slots to 1...but to be honest, (the thing still kept hanging - I tried various different Torrent software Bitlord etc. etc. and the only one that was reliable in recovering was VUZE - I Hate it, but if your router, modem keeps hanging, then it is the best one to go for.
The biggest improvement was getting rid of the Billion modem and smashing the D link router (DIR 615) with a hammer! -good luck - I pestered TOT for months over this, and it seems it was my problem all along - also, limit the number of torrents you try to download at the same time, depends on your connection, but I have a 3MB line and no more than 3 or 4 seems to work best.