Bell Wireless Home Internet - inbound OpenVPN UDP packets not arriving

[Agricol]

I have Unifi gateways at two sites and am attempting to establish an OpenVPN site-to-site VPN. One of the sites connects to the Internet via Bell Wireless Home Internet. The other connects via a fibre connection with a public external IP address. Both sites use dynamic DNS to associate their host names with their respective public IP addresses. On the Bell side, I am not using the Bell-provided modem. The Unifi gateway is connected directly to the Wireless Home Internet antenna device.

Doing a tcpdump on both ends and monitoring packets to/from port 1194, I see the Bell side sending out UDP packets to the remote site and see them arriving at the remote site. I see the remote site sending out UDP packets to the Bell site, but they never arrive at the Bell site.

Given that the Bell site is assigned a private IP address by Bell and uses CGNAT, I thought that might have something to do with it. I called Bell Support and was assured (very emphatically) that there is nothing on their side that would prevent an OpenVPN connection from working.

Does anyone have any suggestions as to what is happening here and how I might fix it?

[dks]

Thank you for your question. As this is a peer to peer site and can only comment on Bell equipment, which you are not using, unless there is a forum user with similar equipment and experience, we can’t really answer your question. You might find posting to Reddit will give you the deeper and more knowledgeable answer you seek. 

[Agricol · Accepted solution]

Thanks for your response, @dks.

In continuing to try to figure this out, I discovered Ubiquiti's Site Magic SD-WAN feature which makes it very easy to connect multiple sites. I set that up and it works, so I will likely go forward with that rather than try to debug the OpenVPN issues.

[dks]

That’s a wise and prudent choice. Well done.