Thanks for looking into this. But this sounds very strange to me. I never listens to radio playing in a grouped zone.
And what is also strange is that I never have any dropouts or stopping when playing tracks from Qoubuz in Roon. No matter if I play to one of my endpoints or to a grouped zone.
My Router is Asus RT-AX86U. And the network and wifi is strong, I never have any other problems.