For a few days I had 6 vms happily running with NAT networking, they could all talk to one another with ips in the range 192.168.122.xxx.
Now for some reason they have lost most connectivity.
The vms cant ping externally nor can they ping eachother, but they can ping the gateway pf 192.168.122.1 on the host Alma-10 box
Actually, this is such a showstopper that I am going to install Fedora 10 instead 
Hello
Is the host OS Almarinux?
Please try stopping the host’s firewalld service temporarily
and verify if you can connect to the external network.
Based on the symptoms, I suspect IP masquerading isn’t working properly with the host’s firewalld.
Thank you
Yes host OS was Almalinux. I was running Fedora on my desktop PC but it destroyed itself after the first OS update, I tried it twice and twice it destroyed itself twice. So I turned to Almalinux and things worked fine for a week and them and then the vms lost the network. I don’t remember doing anything to cause the issue. I tried to disable the firewall but it did no difference. Of couse I could have run tcpdump on the interfaces to fry to find out what was happeneing, but I just gave up and installed Ubuntu And it seems to be working fine for the moment !
Thanks for your response
George