Have you tried doing a reset on it? And then add it?

How to Factory Reset Sonos Sub Mini

Yes I have reset it for more then 10 times and every time same issue.

I would perhaps try cabling it direct to your router ‘temporarily’ and then try the setup again from its reset state. Then if still no joy after that, it maybe best to submit a Sonos system diagnostic report from within the Sonos App, note it’s reference and then contact/chat with Sonos Support Staff via this LINK and see what the Staff can perhaps suggest to resolve the matter.

Assuming the change of ISP brought a change of router, and the system’s connected to the WiFi, the problem could be with the router refusing proxied IP requests. Which router is it? 

Yes @ratty is probbably correct here. I was thinking that the sub-mini was not adding to the Sonos App during its setup from its factory reset state and was perhaps having trouble getting a firmware update, but looking again at the initial post and the screenshot, it looks like the sub has actually been added to the system and then simply not ‘bonding’ to the Home Theatre setup …and that does perhaps infer an IP address ‘proxying’ issue with the router, albeit I’m surprised to see the surrounds remaining in situ in that screenshot.

Wiring a device to the router often resolves the IP address ‘proxying’ issue and if that suggestion does work, then it would be best to wire the soundbar to the router in the longer-term, albeit wiring the sub temporarily to the router might resolve the issue, it’s just not an ideal situation to leave the sub wired.

Don’t wire the sub unless there’s another component, such as the Playbar, wired as well. A home theatre satellite cannot be the sole wired device.