Like I have the same router and no problems between it and the 770, so an upgrade would be a waste of money. Things to check in order.

When you scan with the connection manager (click on connect) does it show your home network?

If you 770 doesn't see you home network you'll have to check to see if you're broadcasting ssid. If not, you'll have to enter your network by hand. (the down arrow next to the words connection managet --> tools --> connectivity settings --> connections --> new) If that doesn't work check:

Maximum Number of DHCP Users
make sure your key matches for what ever security you're using
wireless macfilter (if using add your 770, if not then it don't matter)