Seen this on a BT site and also on BBC -so it might be of interest to those on BT bb.

https://www.bbc.co.uk/news/technology-56949262?fbclid=IwAR2f0oaUs8PGr66AJZtJWST0-sxPdPZjqHOAcuflQ6GvNxbqnDNnEzU3KRE

BT Smart Hub 2 router 'disrupting' home networks

"

The telecom giant's router operates using two different wireless frequencies: 2.4Ghz and 5Ghz.

Users are complaining that any devices not linked to the same frequency, such as a phone and a speaker, are refusing to communicate with each other.

BT is offering firmware updates to those affected."

 

Sounds like the default firewall rules were set up to be more secure and treat them as seperate networks rather than home users where it's all one.

These things happen and hopefully a week later BT have posted an official software update to the affected routers.

From what I'm reading on BT sites an update is filtering through.