I'm on a router connected to Verizon's FIOS.
The other person's PC is connected directly to a Verizon DSL modem.
If I issue a Remote Assistance invitation to the other PC, it can get to my desktop: no problem.
OTOH, if they issue an invitation to me, I'm unable to connect to their desktop.
All the appropriate checkboxes seem tb checked.
I'm wondering it if might be something connected with the other PC not being behind a router.?