For those that come across the same issue and google leads them to this conversation: check if ssh isn't using your local user ID for the connection (yourlocaluser@omega-ABCD.local). Use the command like this: ssh root@omega-ABCD.local.
I have the same issue and I'm currently making a new topic for it (Lazar asked me to do this after I first posted to the ticketing system).
A friend and I managed to hack into the omega by interupting the boot sequence an replacing init with sh. Then we were able to see the crypted password, wich in turn googled to the string '5up'. This seems to be the OpenWRT standard root password.
I've decided to make a new reply.
Minutes ago I've tested to connect my Omega and my T520 without limitations to the 802.11b/g/n. What shall I say? It just works fine for both devices, so there seems to be some problem with my router at home.
Therefor I'd say that this problem is solved.
Thanks to everybody who helped me!