I thought I'd share this as it may hopefully help others. I worked on a site where Sky Q mini was saying connected to network and connected to main Q box but no picture or tv guide. Both boxes are connected by Ethernet directly to the switch in the rack. I spent a whole day fault finding and found that one of the Samsung TV's (brand new Oct 24) was causing the sky connection issue. At any time the tv was connected to the network whether that be by Ethernet or WiFi with the Ethernet cable unplugged the sky Q mini would lose its connection. I've spent years in the AV industry and never come across anything like it. I've left the tv disconnected from the network and now using IR to control it instead of IP but at least the sky finally works. If you've tried all the setup process and checked cabling etc, I'd suggest removing everything from your network apart from Sky to see if the sky works. If it does, something on your network is causing the issue.
