For several years I've had dropped download problems and couldn't watch any videos either. I tried another DSL modem and two different routers, Trendnet and Belkin, but the problem remained. I had the same problem wired and wireless. Two weeks ago I bought a $2 Linksys router at a garage sale, installed it and now everything works fine. What could have been wrong with my equipment? I never changed any settings but left everything at the default settings other than security.
Was the LinkSys self-configuring? (The newer ones are.) If so, go through the router's bios settings and see what, if anything, is different from what you had been using before with your other routers. I know that you manually changed the security settings, but something else could be different, too. You didn't say what you were using as a DSL modem at present, either.