7.6 problems connecting

[Lou1z]

since upgrading to 7.6, my duet receiver won't connect in hybrid, wireless or bridge mode. my controller does connect to the wireless network.
my 3 x booms, 1 x sb2 & O2 joggler running squeezeplay all connect without issue.
the receiver runs through it's normal proceedure eg red, amber, then stops at blue and will not connect to my SBS or squeezebox.com.
it gets an ip address via ethernet (goes blue) but that is all it will do.
it doesn't get an ip address via wireless (stays yellow) and that's it.
should i be able to ping it because i can't get a reply when it's on ethernet.

if i revert to a previous version (as i've tried everything else), will the firmwares downgrade on my booms etc

regards,
louis