Wed May 30 00:35:54 2018 **** 55973 IP packet with unknown IP version=15 seen
Check comp-lzo option both server and client configuration file. If “comp-lzo” is off in sever.conf and it’s on in client.conf, then a bunch of messages is appeared in server log.
I strongly recommend to remove comp-lzo option. This option makes some troubles. (i.e. ping / icmp packet).