Hello MarkLL:
I am trying to make Grandstream HT286 work with a Zyxell Prestige 6000 router which has a symmetric firewall and, hence, STUN won't work. You mentioned that your router is Draytek 2910V. Does this have a symmetric firewall?
In any case, can you help me with how to configure my ATA behind a symmetric firwall to work with Voxalot?
Thanksalot