Try factory reset the device, then setup the device after:
 

1. Unplug the power cord.

2. Depending on which product you have, press and hold the  Bluetooth button (Era 100 / Era 300) while you reconnect the power cord.

3. Continue holding the button until the light flashes orange and white.

4. The light will flash green when the process is complete and the product is ready to be set up.

Thanks, Kaizos. Yes, I tried that approach a few times, but I get the same result unfortunately

What did Sonos Support suggest, when you called in?

Hi Airgetlam. Sonos support couldn’t find a problem with my setup; I gave the team full system access … we spent a good hour going through router settings etc but it was inconclusive. So I sent the speaker back and received a replacement. I have just bought a USB-C to Ethernet cable and will attempt to update the speaker via hardwire, rather than wireless … that’s the only thing the Sonos support info suggests, that I haven’t been able to check so far. A bit annoyed to have to spend another £40, but if it works …

In that case, it is more likely that your network is blocking sonos app in updating your era 300, refer to your network provider in this issue.
-also make sure that you are using only one version of sonos app, sonos icon with orange background.

router's firewall/ parental control settings for any rules that could be blocking the player's connection.

And, if not firewall, there are other things that can block access, such as virus protection apps, VPNs, port blocking software, etc. 

Thanks again Kaizos. Yes, I went through all of the router settings with SONOS support and there were no obvious issues. Also, I haven’t had any problems updating any other hardware previously.

I have deleted all SONOS apps on all devices and only have S2 (orange) installed

Thank you for your suggestions

since ERA 300 is a new device, please update this thread when your issues are resolved using hardwiring USB-C to Ethernet. i am intrigued

have you tried turning off the device and turning on Again? unplug and plug. no factory reset needed

Hi Kaizos. yes, I have tried that. But thanks for the idea.

how about different wifi network or service provider? like someone you know in the neighborhood, if they don’t mind, just for your device to be updated

.

1. Set up the player as a new household
2. Update the player
3. Factory reset the player again
4. Add the player to the existing household
   this might be a good try

Thanks, Kaizos. I have thought about that option - and will try it if I don’t have any success with the Ethernet connection, when it arrives. 

got a new intel about updating over wifi connection, try removing any special characters in your wifi network, in wifi name and wifi password if there is any.

Thank you Kaizos and Airgetlam for the various guidance and advice received.

I used an old router of mine and the update went through fine; ERA 300 up and working.

I’m still working with TP Link support to establish what is fundamentally wrong with my router settings, so I can continue to update the speaker as necessary in the future.

But my immediate issue is resolved.

Many thanks.

Hi i am stuck with the some problem.  Did someone have solve the problem? Currently my system (2x Era 300) is not operational as it is stuck during the upgrade process of the Era300. By accident i have a TP-LINK router and a TP-LINK Wifi Mesh. SONOS Support could not help to resolve the ssue. It is very annoying. Have someone be able to understand wat is going wrong?

Error 30? See https://support.sonos.com/en-gb/article/error-30-when-updating-sonos

You can start by simply rebooting everything. Power off the router, mesh and Sonos units. Restart the router and, when it’s fully ready, follow up with the mesh and then the Sonos units.