The 5 Ghz network on my router keeps failing. It says it's enabled but network doesn't show up; light not on. I'm in dual band mode and 2.4 still works fine. I did factory reset, both networks looked good, then restored config and 5 Ghz was working briefly. After a little bit the connection dropped; switched back to 2.4 and that's working as usual. When I looked again the network had disappeared again. Configuration is identical to 2.4 and the only things I've changed from factory are the login. Didn't use to be a problem - I've been using this router for years.