I don't have Sonos so this is not from experience, but:
- I don't believe Sonos supports 5GHz wifi so if you haven't already, consider splitting the Wifi frequencies and giving each their own name. See How do I split my BT Hub's SSID (wireless network name)?
- You could try changing the 'mode' of the Wifi on the Home Hub. If you go to http://192.168.1.254/gui/#/advancedWifi and scroll to the bottom of the page you'll see any option to change the mode between 1, 2 or 3. There's no detail as to what this really does, but it's apparently helped with some devices that had problems connecting.
- I found Switching Sonos to a new WiFi network. I've included in case it's helpful to you or others, but if Sonos were working on this with you these steps have probably been tried already.
I gave up on the SmartHub. One of the issues was the Gramofon music devices I use (poor mans Sonos) was not compatible with the SmartHub 'technology'.
I did start a discussion on the subject:
I have just moved from Virgin to BT
I was supplied with a Smart Hub
Although my internet access was perfect, I could not connect properly to my Sonos System, my Zmodo wifi Cameras or my Hive System.
Sonos, Hive and Zmodo all said the same thing, that they were experiencing connection problems with the Super Hub. They all said that the Hub 5 was a better Hub (at this time).
I spoke to BT and they very kindly supplied a Hub 5. Now, all my wifi gadgets are connected and working fine.
I am sure that the Super Hub will soon have a firmware update and prove to be the better Hub but, for now, if you have a Hub 5, don't upgrade just yet.
....same for me - all working perfectly on Home Hub 5, and then could not get Sonos to connect reliably to the new Smart Hub 6. In the end I went back to the HH5, and subsequently ditched the HH altogether and got an alternative modem / router from TP-Link. This connected faster, has better wifi range, and works with Sonos with no issues. The Smart Hub 6 appears to be a partly finished product with very buggy firmware. Perhaps it will be OK after a few update cycles.