One I've read works is 8.C.H.2, my friend also got the same router from his new ISP (Sonera here in Finland) last week and so far so good. It's been working well and we haven't actually ran into any problems with it, although haven't been gaming nothing but Dota 2 on it. Didn't actually remember the check which firmware it had. Hope you get it working one way or the other.