OpenVPN on IDNet

[benjanyan]

Hi all. Not long signed up here and fairly new to IDNet.

I'm having issues maintaining a VPN connection to a server in the Netherlands. Specifically, it seems to stall randomly so there's no connectivity all of a sudden. This seems to be specific to UDP as TCP seems to work okay. Don't want to send you to sleep with too many details as my question is a little more simple.

Is there anyone here on IDNet successfully running a UDP OpenVPN connection? If there is, it'd be another step towards crossing another one off this massive list!

Cheers.

[Simon]

Hi, and

Have you discussed this with the IDNet support team at all?

I'm afraid I'm not in a position to offer any advice, but hopefully somebody will be along in due course that may be more helpful.

[benjanyan]

Thanks, Simon.

Not yet, there's a few other things I'd rather rule out first. My newish Asus DSL-AC68U is one of them (I was using the dreaded VM SuperHub2 before!)

[nowster]

OpenVPN works fine on iDNet. I've been using it for 8 years.

You might need to constrain the MSS/MTU values.

eg.

fragment 1300
mssfix

[benjanyan]

Thanks, nowster. That's good to hear.

I tried various mssfix values already but looking at the docs, that only influences TCP packets inside the VPN. I'll have a play around with fragment too and see what happens.

In the meantime, I've set another server up in the UK (I've got VPS coming out my ears) and that seems to work absolutely fine, frustratingly. No tweaks necessary.

[benjanyan]

Think I've made progress.

The seemingly random stalling I was seeing was due to duplicate IP addresses on the VPN side (there's a couple static ones and bunch of dynamic).
It came to light when I found I could ping the client from the VPN server but not vica versa. I tried to SSH to it from the VPN server and discovered it wasn't the machine I expected. D'oh.

With fragment 1400 and mssfix, it's been fairly stable so far. I was experiencing the odd drop and stall before the config changes causing the above. I just assumed it was the same issue that'd gotten worse!