Are you sure that the Roam isn’t actually working okay here, but that your controller device is just not discovering the device on the LAN? 

When the Roam starts up from a fully powered off state, it’s top-front status LED will normally flash during boot-up, indicating it is looking for an IP address from the main router - when the IP address is assigned the status LED will then stop flashing and becomes a steady light. If that is what is happening in your case, then…

The Sonos controller uses SSDP to initially discover the players, multicasting via UDP to 239.255.255.250:1900 and, for good measure, broadcasting to 255.255.255.255:1900. After that communication is unicast.

It ‘might’ be the case that your network is perhaps having issues with SSDP and so the Roam is fine, but your controller App is simply not discovering it?

When it’s status light is steady, are you able to ‘ping’ the Roam across your network - and/or does it show as connected within your router?

Can you perhaps check that the routers Wifi bands are not isolated in the routers configuration pages. Whilst logged onto the router, if you encounter a setting labelled ’IGMP Snooping/Discovery’ or similar name, then perhaps enable that setting.

Is the network LAN subnet segmented, perhaps by different wireless networks/extenders operating on different wireless channels? That may cause discovery issues in some instances. Try switching off other wireless access points, just as a test, and just leave the main router WiFi AP only for devices to connect to - see if that makes any difference.

It’s also possible aswell, that the mobile device is where the problems may lie here…

Is there any VPN, Firewall software, ‘Private Address’ (MAC Spoofing) or ‘WiFi calling’ enabled on the controller device, or any other security software that might be blocking the mentioned discovery communication? If so, try temporarily disabling those features and then see what happens.

So ideally, you want to put the Roam and the mobile controller device on the same access point and same WiFi band, just as a test and to see if that allows the speaker to be discovered by the Sonos App? If this, or the other things mentioned, do work for you, then it’s likely going to be a network issue, rather than an issue with your Roam.

I would also strongly recommend to not repeatedly factory reset the Roam as that is unlikely to resolve your issue - such a reset is normally done on rare occasions only and mostly only as a very last resort.

Hope the above information and suggestions help you to begin to resolve your issue.

Hi Ken,

Thank you for the detailed reply. To answer some of the questions, yes when I power on the Roam it blinks white for up to a minute usually a few seconds and than its solid. I never checked if it got an IP (i assume it did because of the status light but next time it does it I will check if i can ping it).

Now in terms of network setup, i am running an eero - 4 access points mesh, all erro 5. From what I know the Sonos only connects on 2.4 band, my phone and tablet are 5Ghz compatible but as i said have no issues accessing and playing music on all my other Sonos devices, just the roam.
The network is not segmented and to try and force my phone on the 2.4 GHz band is something i tried by disabling the 5Ghz in eero for 10 mins but that did not make the Sonos app find the roam.

Does the Sonos Move use the same implementation when powering on or is it different? Reason i am asking is I know someone who has a Move who would be willing to lend it to me for a few days to runs some tests to allow me see if this an issue with my network or with the Roam itself.

@Rubbinio 

Yes, as far as I’m aware the Move works in much the same way as the Roam, so it’s perhaps worth trying.

I have 2 Roams. One has worked flawlessly. The new one kept dropping offline or disappearing from the app. I would have to reboot or reset the new Roam only to have it drop off again. I called support 5 or 6 times and nothing worked. 
 

Recently I moved a bunch of connected devices around and moved the “bad” Roam to a different charger. Voilà! Problem solved! (so far). It hasn’t dropped for 2 weeks. Now I have it on a wireless charger with a Sonos plug. Unfortunately I can’t remember what it was plugged into when it kept dropping but I think it was a higher amperage quick charger. 
 

Good luck. 

I’ve had a Sonos Roam for a year or two. It’s constantaly disappearing from my Sonos system. In my opinion the problem is that the Sonos Roam is a piece of crap. I’m happy with my other Sonos speakers (six of them, not including the Roam). But I’m very disappointed in the Roam. I wouldn’t recommend it to anyone.

When, in fact, it’s much more likely your network. I’d be looking at either simple wifi interference , or possibly duplicate IP address issues. 

However, if you think there is a fault in your Roam, I would recommend that you submit a system diagnostic within 10 minutes of experiencing this problem, and call Sonos Support to discuss it.

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