OVPN connection stopped working recently

I’m using a L009UiGS-2HaxD-IN router running the 7.13 version of OS. I added new open-vpn connection using import-ovpn-configuration command in late December last year.
Suddenly it stopped work recently: it was working last Tuesday.
I receive the following entries in logs:

ovpn-import1705068422: initializing...
ovpn-import1705068422: connecting...
ovpn-import1705068422: disconnected <poll error>
ovpn-import1705068422: terminating... - poll error
ovpn-import1705068422: disconnected

on and on.
I’ve already tried to update to 7.13.1, but it didn’t help. I also tried to remove and re-create ovpn connection.
I received following warning during ovpn connection creation:

unsupported configuration parameter 'setenv'
unsupported configuration parameter 'socket-flags'
unsupported configuration parameter 'push-peer-info'

Never mind. ISP blocked port