OPENVPN keep crashing

[cyberbot]

Hi guys,
we are using 2.3.3-RELEASE-p1 (amd64) on a hardware,
the issue start today, the users can't log in using the VPN, after i check i see on the VPN that the users are already logged in.
after i stop the openvpn services and start it again, stuff start working, while the users connect once, and disconnected can't log in.
what i have noticed is the pfblocker keeps crashing too, so have to start it everytime manually, is this a related issue to the vpn?

Can you please advise what could be the issue ?
thank you

[cyberbot]

i have noticed one user has forget his VPN on while he is on the office,
he is connecting with the VPN from the LAN, when i disable his connection VPN start working.
is there is a way to fix this ? even when the users forget to disconnect their VPN on the LAN won't cause the openVPN server to crash.

is this related to the Crypto: AES-128-CBC/SHA1 D-H Params: 1024 bits we are using?