Hubmesh issues stoping access

Hi a bit of a freaky one but it's causing me serious issues.
I have 4 hubs 2 x c-7 and 2 x c-8. C-8's are just there bing evaluated whilst I decide the new topology of the network.
The problem is the primary c-7 which interfaces with Echo Skills and Homekit has started with an odd but major issue for me.
I have hub mesh between all 4 and it has been stable for a while. I noticed some devices stoped reacting to voice commands. Various reboots etc sorted it.
About a day ago I noticed that I could not connect to the main hub directly across the local network from phone app or browser on net. BUT could access via remote access from the registered hub page.
To cut a long story short it appears that the hub mesh on the primary hub is affecting the LAN connectivity.. yes it sounds daft and I have swapped switch ports, cables and moved to another switch. The mesh will not connect from the primary hub, all others are fine, and I have regenerated tokens on all hubs disabled, rebooted, re-enabled, re-booted and its still the same.
Have I got the basic principle of the hub mesh wrong and I shouldn't actually have links to all hubs from all hubs? and this will cause network loops?
In the disabled state I can get to the hub via the IP address.
Any ideas? Or do I need to mobilise the big guns at Hubitat?
Thanks in advance.

Update:- By disabling all mesh configs and bringing up the primary hub and the second c-7 without the c-8's I have connectivity again. I will leave the other 2 disconnected for 48 hours and then introduce them again one at a time.
Any postulations on this issue would be much appreciated.