How to force Volumio Pi to connect to the wifi repeater

I have 1 Pi in the bedroom connecting to the network/NAS via wifi.
The wifi is usable but not stellar.

I had bought a 2.4G wifi repeater (i.e., same SSID as the main router) and I can verify I can get better throughput (27mb/s flucating vs constant 50mb/s).
The issue is the Pi connects to the main router instead of the wifi repeater.
Is there a way to force the Pi to connect to the wifi repeater?

Thx.

Use a different ssid for your repeater??

Prefer not to do that but I may end up doing that.

Even I use a different SSID on the repeater, Volumio still tries to connect to the router via the old SSID.

How do I delete the password of the old SSID on Volumio? Thx.