Netatmo Doorbell keeps disconecting?

[duckdodgersuk]

I've a Netatmo Doorbell and if I try to connect to it in the app it just says "An error has occurred"

If I reboot it , it will work for a day or so but then it happens again.

This is my 2nd Doorbell from them and like the last one it will work for about 6 months then its starts erroring.

Tech info 

• Sky Home hub's wifi is split to 2.4ghz and 5ghz 
• Sky Hub SR203 Firmware  = 7.02.0804.R
• Doorbell Firmware  = 2.22.4
• Doorbell powered by Netatmo transformer (No Chime)
• Sky Hub is next to front door.

I think it might be an issue with IPV6 as my Other Netatmo presents runs on IPV4 and is fine. 

I cant see any way to force it to only use IPV4.

Is there a way to add a firewall rule or disable IPV6 for just the doorbell?