I have a persistent VPN established from my iPhone, to my OPNsense router. Historically, the VPN has always remained on, continuously reconnecting whenever I switch from WiFi to LTE, and back. Now every time I check, the VPN is disconnected. I reconnect it, it connects fine, I can access resources fine. Yet I'll look later, and again, it's disconnected.
What are the steps I should take, to figure out why the app won't stay connected, and reconnect when disconnected?