In my case, I received the following from SE. Setting the HTTPS mode to "HTTP and HTTPS enabled" solved the problem for me.
(Norway is still on the old version of the "Wiser for KNX" app)
To set this mode: Go to "Services" and "HTTP server" and then check the field "HTTPS mode".
FROM SE:
-----------------------
There is a recommendation from our developers:
we have found a small bug in firmware 2.8.0 regarding VPN connection. When the HTTPs is enabled as we recommend in pop up window after firmware upgrade and accepted the VPN is not working. This can cause an issue with our old Wiser for KNX remote app.
If it is your case activate back HTTP and HTTPS enabled option in HTTPS mode.
(Norway is still on the old version of the "Wiser for KNX" app)
To set this mode: Go to "Services" and "HTTP server" and then check the field "HTTPS mode".
FROM SE:
-----------------------
There is a recommendation from our developers:
we have found a small bug in firmware 2.8.0 regarding VPN connection. When the HTTPs is enabled as we recommend in pop up window after firmware upgrade and accepted the VPN is not working. This can cause an issue with our old Wiser for KNX remote app.
If it is your case activate back HTTP and HTTPS enabled option in HTTPS mode.