Why doesn't Disney Plus work despite good Wi-Fi?

I have the Disney Plus app on the TV (via the Fire TV Stick), PC (via the website) and the smartphone (via the app). With none of these devices, Disney Plus does not open or you are given the opportunity to log in. It doesn't work with an Ethernet cable either. When I switch off the WLAN on my cell phone, the app works with mobile data. So it seems to have something to do with Wi-Fi. But I have no idea what it is because the Wi-Fi strength is good and apps like Netflix or Amazon Prime also work.

Can someone help me and maybe have a solution?

Restart the router

Thank you, that worked.