Poly / Obi 2182 Ring Group Issues (delayed or extended ring)

Hi folks:

Hoping someone can help.

I’m using a Grandstream 750 along with a Poly / Obi 2182, separated into sub-accounts and in the same ring group.

I’m having two issues every few days:

  1. The Grandstream will ring first, followed by the Poly 5-10 seconds later. I am then unable to answer on the Poly.

  2. When answering a call on the Grandstream, the Poly will continue ringing.

Setup: TLS is enabled, along with keep alive and NAT. I have made changes to the registration period, but with no impact. It seems like a firewall / NAT issue. SP1 on the Poly is a Google Voice Line for my out of state parents. (My only reason for keeping this phone) The Poly is also running on WiFi. It worked well until I turned on the ring group.

Question: are there other settings I can try? or should I hardwire it and turn off wifi? [#2 irritates my wife badly]