subs not showing but they are hooked up

It’s not possible to have two Sub Mini’s bonded to any Sonos soundbar. See below and/or click this link.

Using two Subs with your home theater speaker

Some Sonos home theater speakers can connect with up to two Subs.

• Arc Ultra: Compatible with two Sub 4s, Sub (Gen 3)s, or one of each.
• Arc, Beam (Gen 1 and 2), Ray, and Amp: Compatible with all Sub models in certain configurations:
  • Sub 4 can be used with another Sub 4 or a Sub (Gen 3).
  • Sub (Gen 3) can be used with a Sub 4, another Sub (Gen 3), a Sub (Gen 2), or a Sub (Gen 1).
• Playbar and Playbase: Compatible with Sub (Gen 1, 2, and 3).
  • At least one of the Subs must be a Sub (Gen 3).

If these are set up as two ‘rooms’, one with the Arc, the other with the Era 300s as a stereo pair, there can be two Sub minis connected. But why they wouldn’t show up in your controller is more confusing. I’d be tempted to first try a network refresh, by unplugging all your Sonos devices from power, and while they’re unplugged, reboot your router. Give the router two minutes to come back up, then plug in your Sonos devices, and give them two minutes to boot up and reconnect. Note that the Subs connect directly to their ‘bonded’ speakers, but get IP addresses from your router, but they’ll show in the controller as part of the ‘room’ that they’re bonded to, and not as separate ‘rooms’. 
 

I think that will resolve the issue. If it doesn’t, check your system for updates and apply them, and if that doesn’t work, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it. Don’t post the resulting diagnostic number here, their lawyers get sensitive about GDPR.

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 Support staff, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.

Both sub mini are hooked up to the Arc. There is an App that lets you do it. Even tho they say it can’t be done. I did it

Both subs are hooked up to the Arc. There is an app that lets you do it. 

Then you may want to check with the makers of that app as to why they’re not showing up. This is a Sonos community board, and as ​@AjTrek1 says, Sonos doesn’t support that. 

I know. 

As ​@Airgetlam says….contact the developers of the 3rd party app. Since Sonos doesn’t support two sub mini’s bonded to a soundbar the Sonos App will not display them as such, or it will show them as you have indicated “not connected”. There’s nothing that can be done about it.

But least they are working. 

It would be interesting to see what Sonos support has to say about this.

Submit a diagnostic and call them, let us know.

No thanks. I found a loop hole for them to work