WSL2/VM TLS Handhake failed

Recently I was very annoyed by random TLS errors, for example:

kubectl get pods
error: couldn't read version from server: Get https://master-ip/api: net/http: TLS handshake timeout

I was receiving those errors during executing kubectl commands, pulling docker images, execuing curl or even while copying data via ssh. And what’s worse, those errors were random, without any regularity. I’ve even spin up totally new WSL2 instance with Ubuntu instead of my old Fedora VM to get rid of those errors.

After spending some time investigating, I’ve found issue: HTTPS connection if Windows is using VPN#4698

As it turned out, my work VPN were reconfigured, and now VM or WSL2 had to use smaller MTU, 1350 is my case. Since tls encrypted frames weren’t properly encoded/decoded, I was receiving errors on large packets.

To set up MTU via nmcli:

sudo nmcli connection modify "Wired connection 1" 802-3-ethernet.mtu 1350

Since WSL2 doesn’t have init system running, put following command in .bashrc or, in my case, fish configuration file:

sudo ip link set dev eth0 mtu 1350