Not really much information here. You’re using S2, I presume? Tell us about your network, how your Sonos device(s) are connected, please. You’re using the ‘add a device’ function in the controller? Is this One SL new, out of the box, or has it been part of another system, and would need a factory reset before it can be added to your system?

Brand new Speaker.  I added the mobile speaker without any issues.  This speaker plugs in and utiizes my wifi network

Yes the speaker is brand new

I’d try a factory reset of just that speaker, just in case, then wire it temporarily to my router before trying to ‘add a device’ process.

If that doesn’t work, I’d call Sonos Support directly to discuss it.

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.