RBR 40 dropping internet since firmware upgrade to V2.6.2.104

Model is actually an RBR40, but that model isn't listed

Connected as Router to Verizon FIOS ONT. 

Was rock solid until last weekend when I upgraded the firmware to V2.6.2.104.

Now certain devices (wired & wireless) are unable to access internet, but still able to access all local services / devices

Issue appears to affect "new" connections to the orbi.

Router page indicates Internet connection is "good"

Workaround is to have the router "test" its connection after which full internet connectivity resumes.

I am at a loss aa to next steps.

Can the firmware be rolled back on the router?

Other ideas?

Ed