Hallo,
so here are the brand new results of the last hour:
Markus from urfdb project found the issues an he created 2 new betas of ufdbGuard during our conversation.
The last beta V 1.26beta6 is working now on my raspi --> so that my project with a router for the kids is ready for daily use now 
I’ll ask Markus to provide the new sources for testing as soon as possible.
I was able to build a RPM with the original spec from ufdbGuard SRPM…
with warm regards from snowy and stormy Leipzig
Denis