The default MTU(Maximum Transmission Unit) is 1420 in wireguard, while the most other devices use 1496 or 1500.

Read here for more info.

TL;DR

Stop the wireguard interface in use:

sudo systemctl stop wg-quick@wg0
# or
sudo wg-quick down wg0

Edit the wireguard config file:

sudo vim /etc/wireguard/wg0.conf

Add MTU=1400 to the Interface section like this:

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[Interface]
Address = 10.10.10.1/24
SaveConfig = true
ListenPort = 51820
MTU = 1400
PrivateKey = xxxxxx

And start the stopped service:

systemctl start wg-quick@wg0

Add the same for the client config.

That’s it.

Happy networking!