Check reverse tunnel status
To check if your ssh tunnel is active and running, you need to ssh into your UniFi Controller using command
ssh root@<UniFi controller's IP address>.
Log in using the password that you have set on your UniFi controller under SSH settings.
After you've logged in to your controller using ssh, check the status of tunnel service using command:
systemctl status spotipo-tunnel.service
(this is the name of the service if you've followed this article)
If the service is not available, using this same command would return a message similar to this.
This means that the service is probably stopped or it was turned off after an update and simply needs to be restarted. To do that, use these commands.
systemctl start spotipo-tunnel.service
systemctl enable spotipo-tunnel.service
When this is done, check the status of your service using the command:
systemctl status spotipo-tunnel.service again.
If your tunnel is now active, the message should now appear like in the picture below.
Verify the connection
After this is done, check that the status of UniFi controller in the Spotipo settings is Online.
Also check if captive portal is working properly after these changes.