Tailscale routing problem

23rd February 2026

When you use Ubuntu as a tailscale router, IP Forwarding is turned off by default, you may get the misconfigured error message below

Solution:

nano /etc/sysctl.conf

Uncomment (remove # at the start of the line)

net.ipv4.ip_forward=1

check:

sysctl net.ipv4.ip_forward

Symptioms:

When IPv6 is DISabled on the local NIC but ENabled on the Tailscale NIC and 4to6 nat is disabled

and the subnet has a combination of Tailscale subnet router AND hosts with the tailscale client installed

tailscale routing gets confused

Can’t ping some hosts, can’t get to shares using local IP address

sometimes fixed by making sure tailscale is up on both ends