Network radio delay between two players

Hi all, I have two ci 580v2 devices for my home setup. They are feeding two Leda amps to power a whole series of loudspeakers within the house. My bedroom and bathroom are adject but are on two different ci580 devices. When grouping both zones in BlueOS, they play in sync as long as i stream from Tidal/ Qobuz or Spotify. When switching to network radio though a delay between both devices suddenly occur. We suddenly have one room playing 4/5 sec later than the other, which is pretty annoying. I tried to reboot both players but this didn’t solve the issue. Anyone who can help.