I still have the problem that if I turn on my RUT955 after a while, I can't connect to the router via OpenVPN. A server is running on the router.
What I noticed is that the router gets a WAN IP with 100.x.x.x assigned. Whenever the router gets an IP with 100x.x.x/8, no connection to the OpenVPN server can be established.
You can ping the router. Furthermore, I have tested that you can ping Google from the router.
I can also log in to the router via RMS.
Something is blocking the OpenVPN connection.
Only after one or more restarts, when the router is assigned a new WAN IP, does the connection work.