After updating several of my Gen4 and Gen3 devices to the 2.0.0 firmware, I ran into several communication issues as well: issue 1 and issue 2 Though I think different than yours.
I switched to the new Shelly Control app that uses a different connection logic. This fixed the connection issues I had.
Also check out the forum topic for the new Shelly Connect app: [APP] Shelly Control - Smart home automation is that easy!.
You can contact the developer of both apps (Drenso) via the contact details on the app store page of the respective apps. They are also included in the first post of the forum topic.
