RAK7289C - OpenVPN connection problem in LTE mode

Hi,
We have a problem with OpenVPN connection on RAK7289C in LTE mode. Gateway sometimes can’t connect to our vpn network, there is no ping to any of the devices in vpn network despite the status page of OpenVPN on gateway that says its enabled and correct ip addess is assigned. The logs on vpn server also point that device is connected. Sometimes after reboot the connection is restored, but sometimes not. This problem occurs only on LTE connection, on ethernet works fine every time. We’ve tested WisGateOS versions 1.3.1, 1.3.3 and 1.3.5.

Our vpn client config looks like this:

client
dev tun
proto udp
remote OUR-SERVER-IP 1194
resolv-retry infinite
nobind
user nobody
group nogroup
keepalive 10 120
persist-key
persist-tun
remote-cert-tls server
cipher AES-128-CBC
auth SHA256
key-direction 1
comp-lzo
verb 3

<ca>
CA-HERE
</ca>
<cert>
CERT-HERE
</cert>
<key>
KEY-HERE
</key>
<tls-auth>
TLS-AUTH
</tls-auth>

Thanks!

Additionaly, when using wifi access point from gateway, the internet connection in very unstable (lost ping to the internet) despite SSH connection to getway beeing perfect and ping to the internet from gateway’s console (through SSH) also working fine.