It is the client config that stopped working after the upgrade(on a RUTX08).
I tried creating a new client config on the RUTX08 but that would still not work, the extra options in the openvpn client config are no longer used (or the topology is somehow overwritten).
For my client to be able to connect is has to have "topology subnet" or else the client will exit on the ip config it receives from the server.
This error message is shown in the system log on the RUTX08 which shows that the option "topology subnet" is never used.
WARNING: Since you are using --dev tun with a point-to-point topology, the second argument to --ifconfig must be an IP address. You are using something (255.255.255.0) that looks more like a netmask. (silence this warning with --ifconfig-nowarn)
For now I will have to push this option to this specific client from the server to make it work.
This is the option that was working in 1.x but not in 2.x