The 403 Forbidden on the variable staging request can sometimes be caused by browser extensions (ad blockers, privacy tools) or VPN/proxy software interfering with requests to our API. Could you try the following: open an incognito/private window with all extensions disabled, log in, and attempt the variable change again? If it works there, a browser extension is likely the cause. If the issue persists in incognito, please let us know and we'll investigate further on our end.

It's strange cause it only happens when I try to change the URL my service is pointing to, to the Tailscale IP. I've followed this docs, but I'm unable to use the IP of the subnet.

The 403 is being caused by our web application firewall blocking the request because the variable value contains an IP address. As a workaround, you can try setting the variable via the Railway CLI with railway variable set YOUR_VAR=, which may bypass the restriction. We're tracking this issue to get it resolved. Let us know if this workaround does not work.