Using exit node problem in GCP

I have an issue:

Instance is connected to tailscale with this command:
sudo tailscale up --authkey=tskey-auth-xxxxxxxxxxxxxxx --exit-node= --exit-node-allow-lan-access=true

If I bring up an instance in proxmox I still can connect to the machine via its internal ip and have full access to my other machines via the LAN-ip.

I want to accomplish the same on Google Cloud, but when I run the exact command I loose all connectivity with my internal machines and cannot ssh into it.

Can someone help me here please? I fully understand that there is difference but Im not able to fix this in GCP, if you can point me to some documentation or tutorial I can follow I would appreciate it very much.