@phaedrux Wow! This is a real fast response. One more reason to be very pleased to pick up an original Duet. Thank you for your prompt answer phaedrux. I can confirm that solved the problem, because meanwhile is what I’ve done and now works again. It seems that the DNS was not resolving the address correctly, isn’t it?
Thank you so much again. Have a nice evening.

Hi all.
My printer has a Duet 3 Mainboard 6HC attached to a SBC Raspberry PI 4 (DuetPi image). Everything is working ok, but all of a sudden it can´t show the DWC page at startup. The browser exhibits this message: “DNS_PROBE_FINISHED_NXDOMAIN”. However if I open a browser session and enter https://127.0.0.1, DWC shows and works fine. What could have been changed/corrupted in the Pi configuration or something? I´m a complete newbie and this is my first build (and post) but from the little that I know this is somenting not related whit the MB firmware but something in the Pi software/framework, am I right?
Could some of you savvy people land me an help, please?
P.S. Firmware is @ 3.4.1 RC1 and Pi was also updated/upgraded via terminal (sudo apt … bla.. bla) few days ago and was working fine.