Client-to-server OpenVPN connection slow after replacement of Fritzbox

drgessi · Dec 9, 2022, 1:40 PM

Dear All,

I am approaching you as I do not have any clue anymore how to narrow down my VPN issue that occured after I have replaced my old Fritzbox with a Fritzbox 7510 (the provider is German 1&1, previous speed 50 Mbit/s, new 250 Mbit/s).

Background:

I was running a pfSense OpenVPN connection (client / server, RDP, IPV4) between two sites successfully for a long time. The scenario is as following:

pfSense (as client) -> Fritzbox -> INTERNET -> Unifi UDM Pro -> pfSense (as server)

I had added IPv4 routes and port forwardings (1194) in the Fritzbox and the UDM Pro accordingly. Everything was running smoothly and I was a able to connect to resources across sites like a charm. Until I was forced to replace the Fritzbox - and I did not have good feelings about that. Anyways, it came as expected and after the replacement and configuration of the Fritzbox, the connection causes trouble. Still I am able to connect to some resources across the sites, BUT at the lowest imaginable speed (its only some kilobytes per second). The only thing that really works is pinging remote resources. RDP fails. Browser applications are damn slow and not usable at all.

I was wondering whether this is a IPv6 issue, or a firewall issue, checked several things, but without success. It's frustrating.

So the question is, if there is someone out there who has a clue how I could narrow down the issue? Like inspecting the network traffic? But how? Any suggestions are highly appreciated.

Thanks
drgessi