I have a Roku 3XS. It worked fine on my old G router, but with this new N900 I am having problems. The Roku only reads the 2.4Ghz band. Once connected, it drops the wireless connection after a couple of minutes and I have to go to Settings and reconnect. This didn’t happen with the old router. All other devices using the 2.4Ghz band are fine. I’m stumped!
have you tried using a static ip on the units? This might fix the connection issues.
Wireless G has a longer range than wireless N, and it may be that the Roku is too far from the N signal, and therefore weaker than the G signal. Measure signal strength at the Roku with a laptop PC. If signal is weaker than Very Good, this is likely your problem, and the units need to be closer. Also, the range of 5Ghz is a lot less than 2,4Ghz, so use 2.4 signal if the Roku gives you a choice. Most Rokus use 2.4Ghz only.
I have to use 2.4 since my Roku 2 doesn’t see 5. Someone suggested I set the router to channel 1 and that seems to have done the trick. Not sure why.