To implement the configuration you described, please refer to the following two guides.
The first guide explains how to configure the router as a Tailscale Exit Node:
The second guide explains how to route traffic received through Tailscale to the WireGuard VPN Client running on the router:
Since you have already run SSH command to do an advertising the exit node status in routes, could you please run the following commands on the router through SSH and provide the complete output?
tailscale version
tailscale status
tailscale debug prefs
grep -n "tailscale up" /usr/bin/gl_tailscale
These commands only check the current Tailscale status and startup parameters and will not modify the router configuration.
The output will help us confirm whether the router is still advertising the Exit Node routes and whether the setting may have been overwritten after Tailscale was restarted or the settings were applied again in the web interface.