https://tailscale.com/kb/1320/performance-best-practices#linux-optimizations-for-subnet-routers-and-exit-nodes

Tailscale version 1.54 or later used with a Linux 6.2 or later kernel enables UDP throughput improvements using transport layer offloads. If a Linux device is acting as an exit node or subnet router, ensure the following network device configuration is in place for the best results:

NETDEV=$(ip -o route get 8.8.8.8 | cut -f 5 -d " ")
sudo ethtool -K $NETDEV rx-udp-gro-forwarding on rx-gro-list off

By default, changes made using the ethtool don’t persistent after a reboot. On Linux distributions using networkd-dispatcher (which you can verify with systemctl is-enabled networkd-dispatcher), you can run the following commands to create a script that configures these settings on each boot.

printf '#!/bin/sh\n\nethtool -K %s rx-udp-gro-forwarding on rx-gro-list off \n' "$(ip -o route get 8.8.8.8 | cut -f 5 -d " ")" | sudo tee /etc/networkd-dispatcher/routable.d/50-tailscale
sudo chmod 755 /etc/networkd-dispatcher/routable.d/50-tailscale

Run the following commands to test the script to ensure it runs successfully on your devices:

sudo /etc/networkd-dispatcher/routable.d/50-tailscale
test $? -eq 0 || echo 'An error occurred.'