Short update…
I have just updated my Firewall… To a new version of Astaro Security Linux, and to a new motherboard. Things were getting really slow with the firewall I think, and it needed to be upgraded. So a new motherboard and CPU. I had a spare HDD so I could have the old and new units running without reformatting the HDD. This was good since I forgot to backup the settings and had to resurect things.
I borrowed about 512 MBytes from my Windows Server for the firewall… And I will see if that is enough. Should be without issue. Minor issue working out which network card was which when I rebooted with the old settings, but all is working now. Perfect…