OpenVPN traffic not passing over new router

[nf1975]

Hi,

My OpenVPN connection has stopped working after replacing my router and I wonder if anyone is able to help?

I have a Netgear Nighthawk X4S R7800 router at a remote site. I configured the OpenVPN setup wizard on this and exported the client files to my laptop at home and I have been happily connecting to the remote site for the last 4 years.

During this time I was using an EE Wifi Mini for my Internet access at home and this needed no setup or amendments to allow the OpenVPN connection to work. I have just replaced the EE Wifi Mini with a Teltonika RUT241 and as soon as I did this the OpenVPN connection stopped working. The connection comes up and the little icon in my taskbar turns green but no traffic is passing. If I traceroute to the remote subnet I don't go past the first hop which is my local VPN IP address.

I tried running a ping from my home laptop to the remote subnet and looking at the traffic on my laptop in Wireshark. I can see packets going to the public IP of my remote router and coming back again and I can see the pings going out but no responses coming back.

I suspect I need to add a route to my Teltonika or open up a port on the firewall, but I've tried various things without success.

Thanks in advance,
Nick