There is a bug related to this issue which should have been fixed in CU185 but unfortunately the updated ovpn.cnf file did not get shipped with the update, although it was specified to be shipped.
It looks like the location that the file is stored in can end up not being correctly shipped even though it has been specified.
A change of location of the file is being looked at and will be implemented into CU186.
https://bugzilla.ipfire.org/show_bug.cgi?id=13595
In the meantime it is possible to implement the changes in ovpn.cnf manually as per this post