mini sub and surround speakers disconnecting after adding to system

First off, stop factory resetting, it won’t help, and is destructive to error logs that might help Sonos help you.

Surrounds and Sub(s) connect to a radio signal, generally, emitted by the soundbar. However, they do receive proxy IP addresses from your router, and I expect that’s where things are going sideways.

Unplug from power all of your Sonos devices. While they’re unplugged, reboot your router. Wait two minutes, then plug back in your Sonos devices. Wait another two minutes, then test.

If this doesn’t resolve your issue, 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.

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.

What router did they give you? Is it on this list?

https://support.sonos.com/en-us/article/incompatible-network-hardware

Common issue with Vodafone routers, resolved by wiring soundbar to router.

Many thanks for the prompt replies. 
it would appear I have a router on the list of “non compatible but with a work round” namely a Techicolor DGM4980VDF. 

I’ll give the hard wire option a try and see what happens. Does the connection have to be into the sound bar and will i need to reconfigure all my other Sonos speakers ( which are working fine)?

In order to have the soundbar communicate with the surrounds and Sub through a wired connection, all of them need to be wired, yes. 

If your other devices are working, there is no perceived need to wire them. 

You only have to wire the soundbar. Don’t select “Disable Wi-Fi” option in the app.

You may also have success wiring another speaker, rather than the soundbar, which is not a surround speaker or Sub/Sub Mini.

See the following support article for what happens in a wired setup.

https://support.sonos.com/en-gb/article/choose-between-a-wireless-and-wired-sonos-setup

Thank you, I’ll give these possible solutions a try and post the results. Cheers 🍻 

Down the line you might consider getting a better router and putting the ISP supplied one in transparent/bridge mode. A better router brings many benefits beyond just Sonos. 

Problem resolved!!

I connected the sound bar directly to the router as suggested. After a few minutes the surround speakers and the Sub Mini automatically connected to the system. I just needed to fine tune the components and now everything works as it should. So many thanks for the prompt replies. 
On the point of my router I was under the impression that it was a good piece of kit with auto 2.4, 5 & 6 ghz selection (or something like that). What is transparent/bridge mode and how would I do that and what would be the benefits? 
thanks again, you have all been a great help. 

No longer pulling my hair out. 👍😁

 Bridge mode is set when you have your own router connected to an ISP modem/router.  Bridge mode turns OFF the WiFi from the ISP modem/router.  It’s best not to have both the ISP modem/router & your router both broadcasting WiFi.

There is a big difference in routers, some list extensive feature sets but many are poorly implemented, like your proxy IP issue here. An aftermarket router can provide the same features, usually done better and additional options.

Also, and this is a big plus for me, if the ISP changes something it does not impact all the effort I have into configuring my LAN. Usually I just swap my Ethernet unlink cable to the new ISP hardware and restart my router if they give me new gear. If they force a reset or update to their router mine isn't impacted, maybe needs a reboot at the ,most.