@thoma 

Hi, welcome to the community.

Usually, as long as the whole Deco Mesh system can get internet service, the network configuration is correct. Besides, there are some small tips that might help optimize the network layout:

1. Since Deco M4 is also a WiFi router as the Sky router,  if you could put the Sky router into bridge mode, there will be only one DHCP server left and all the devices will be under the same IP range.

• But if there are some features on the Sky router that could not be disabled, like VOIP, you could consider setting Deco into AP mode and let Sky be the only DHCP router:

How to set up Deco to work in Access Point mode

Thank you very much and best regards.