I create the Orange to Red rule only to have easier access to my servers and to the www at the same time for configuration purpose.
The plan was to delete the rule after total configuration, so the solution works for me.
But, i guess, a Orange Red rule should not cause such side effects
Adolf
I read the wiki page again and I see that I missed this Tidbit .
By default, IPFire controls the access of all devices on blue using MAC Address filtering. This means that all DHCP leases must be manually approved in the IPFire Web User Interface before they can access the network (including access the WUI from blue network itself)
Thanks I learned something new today.
But you edit the wiki anyway (without knowledge). Sounds for me not correct to do it this way 
It is strange that the mac filter allows access to the WUI.
That was surprising to me.
It did bring up one thought.
If you setup a Red,Blue IPfire. How do you get to the WUI the first time?
I dont know a setup with red blue only, there is always a green in the setup. And green is normal the usual way to admin IPFire