Thanks for the ideas, sadly these are the very first things I tried. I'm leaning towards it now being some kind of redirect issue. OTT Navigator can tune the channels just fine, but TiviMate and Formuler IPTV software cannot. All using same VPN endpoint and same login credentials - identical scenarios but only OTT can tune the channel. The other two report Error 502
I'm experiencing it on both domains indeed
Edit - further investigation finding mostly CA section affected, the US channels working much better