Have you checked your Beam to be sure the WiFi has not been turned off on it in the room settings? Have you rebooted your router?

It might be worth it if you were to submit a system diagnostic within 10 minutes trying the process of adding the Sub, and call Sonos Support to discuss it, or post the diagnostic number here for a Community Moderator to pick up.

There may be information included in the diagnostic that will help Sonos pinpoint the issue and help you find a solution.

When you speak directly to the phone folks, there are more options available beyond just the diagnostic analysis.

Moderator,

submitted diagnostics number 1196771234

please help me get my sub connected properly 

Thanks to @Airgetlam, for helping out.

Hi there @MClary101.

I appreciate your effort in submitting the diagnostic.

Upon checking, it shows that your Sonos system is wirelessly connected to Ruckus. This is a known issue wherein you’re unable to add/pair Sub (or even surround speakers) to a Sonos home theater speaker using Ruckus access points.

We suggest switching to SonosNet by wiring a Sonos player as a workaround.

If you have any questions,  feel free to reach out.

Note that in this case, ‘a Sonos player’ does not include the Sub, or a surround speaker, due to the nature of the connection between the primary and secondary speakers in a Sonos setup. 

Support told me that adding a boost would work. Is that true or did I just order a boost unnecessarily?

I’d suggest it was unnecessary, if you could just wire one of your speakers directly. However, if no speaker is convenient to do so, a BOOST is indeed a good option. I happen to use one. 

Thanks, I guess I’ll know tomorrow if it works since I got expedited shipping. It’s not possible for me to be wired since I use that Ethernet line for my TV to avoid buffering. Here’s to hoping the boost works. 

An unmanaged Ethernet switch is a lot cheaper than a Boost.