VPN Latency spikes

May 25, 2019
I'm running a IPSec/IKEv2 vpn on an ubuntu VM in proxmox and having weird, seemingly random, latency spikes when running the VPN 'externally'.

upload_2019-5-26_12-12-49.png is my 'intranet' is my 'local network' is my vpn network.

So when I connect to my VPN via my latency is <1ms to 3ms as one would expect from an internal network with 1-2 hops.

For IPSec I've port-forwarded UDP ports: 500 and 4500 and when I connect to the VPN via my public-ip, the above happens. average packet times of >1000ms and 50% loss rates.

I used to have a similar setup with virtualbox and ubuntu as host and it worked fine. Now that I've switched to proxmox I have this weird latency issue occur on both IPSec and OpenVPN when connecting from my Public IP, when using my local network ip, it works flawlessly.

If anyone has an idea how to troubleshoot this further, please let me know.
Some more info, when starting the VPN connection up for the first time, it seems to work fine with about +15-30ms extra compared to normal, which is fine because it's a VPN. But after a while it just goes insanely high and sometimes dips back down.

What’s the MTU setting on each end of the VPN?

It needs to be 1450 max as there needs to be enough for packet encapsulation to work, depending of your isp sometimes could be less.

Also run a traceroute to see how many hops and how long each one takes between the 2 points.

Then we have more info to work from.



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