grouping 5hz and 2.4 hz

On the first point - the intent was to hard wire the old router to my existing router to effectively create a second SSID.

On the second, thanks - That explains it.

To the IP issue - Nope, just tried to rename it - I used the IP address from the Sonos sytem to identify the player and change it from SONOS ZP to something more meaningful

I managed to rename others

As you might have gathered, I’ve not tried to do anything fancy with anything as it is way outside my sphere of knowledge!

You can totally ignore the names. They’re not used for anything. 

If it’s a case of remembering which IP goes with which MAC, and which device they represent, I just keep a spreadsheet.

Yep, but useful for troubleshooting like when one stereo pair connects to one wifi disk and the other one connects to a different one = rubbish connectivity!

Update:

On Friday evening, I swapped to a wired set up.

Generally the system is better and more responsive, both from the phone and desktop apps.  The two problem rooms (with stereo pairs) have been Ok, even when grouped together.

I have still got a problem when grouping the soundbar (and surround speakers) with other rooms.  On investigation, I have noticed that the 2 surround speakers are connected to the hub.  All other speakers are not showing up (as expected given they are now using the Sonosnet)

Is it normal? and/or due to the way the soundbar and surround speakers connect to each other?

Look in Settings/System/About. Apart from the Move which will always show WM:1 everything else should be WM:0. Are they? 

Yep, everything other than the Move is WM: 0

I guess it’s a quirk of the BT app