Hello everyone. I have an ER7206 that seems to always prefer the backup WAN. Maybe it's something with my configuration?

The setup is very simple. I have enabled the WAN and WAN/LAN1 ports on the ER7206. The WAN port is supplied by my ISP. The WAN/LAN1 port is connected to a 4G router, as a backup connection.

Under "Link Backup" I have listed the WAN port as Primary WAN and the WAN/LAN1 port as Backup WAN. The mode is currently set on "Backup when all primary WANs fail" with status "Enabled".

Under "Online Detection" I have both ports with the "Operation" mode set on "Auto". They both appear as "Online".

However as soon as I connect my 4G router on the WAN/LAN1 port I can see that my IP switches to cellular data, instead of my ISP's IP. If I disconnect the 4G router I can see that my IP is back to my ISP's IP.

Are there other settings I should check?

Thanks in advance.