I found this article Peplink Cloud Service Public IP Address List
and added IP destination based rules for each of the IP’s. (root, Mars, rwa, ra)
Was a lot of rules… 
the DNS based method sounds easier.
Once I got them setup, it did work as expected. While I was still having issues it actually helped identify that there is also an issue with the cell plan on the LTE WAN at this site. Fun times!
FWIW - Starlink is not rock solid yet…
and BIX Wireless is 
! (throttles to 3G)