Snom D865 VPN firmware bug > 10.1.169.13

All my Snom D865 phones with firmware 10.1.169.13 connect to my FreePBX OpenVPN server ok.

As soon as they are updated to a more recent firmware eg. 10.1.193.14 they won’t boot. After updating, they display a blank screen with the background graphic and get stuck in a reboot cycle.

If I block access to port 1194 via my Firewall, they will boot but show a VPN error. The VPN error is obviously expected.

However, once booted, if I enable access to 1194 again and wait for a minute or two, they connect to the VPN and work ok.

This appears to be a Firmware regression. Is it a known problem and if so, is there a workaround?

If it helps, this is the vpn.cnf file.

client
dev tun
proto udp
remote 123.456.78.99 1194
resolv-retry 60
nobind
persist-key
persist-tun
ca /openvpn/ca.crt
cert /openvpn/name.crt
key /openvpn/name.key
remote-cert-tls server
ping 10
ping-restart 60

We are running FreePBX 14 in the cloud which is behind a cloud firewall. This configuration has been in place since 2018 and I am looking to replace my D725s with D865s.

My experience with Firmware versions is below: -

• 10.1.169.13 – Works OK.
• 10.1.169.15 – Requires port 1194 to be blocked during boot. Once booted and port 1194 is unblocked, requires Identity to be deactivated and reactivated to register.
• 10.1.169.16 – as above
• 10.1.175.10 – Requires port 1194 to be blocked during boot. Once booted and port 1194 is unblocked, VPN is established automatically.
• 10.1.193.14 – as above

Any help and advice appreciated.