Is the WiFi configured to assign the Mac a default gateway while simultaneously not actually providing internet access? If so, macOS will assume internet is available but slow, and will continue to make you wait while it Apple's servers whether the app's certificate has been revoked (for security reasons).
When you disable WiFi in macOS it's immediately clear that there's no internet access and suddenly your convenience starts to matter, i.e. quick launches.
You could configure the WiFi network to not have a gateway set, which would probably solve the problem. The DHCP server configuration simply needs to be changed to not set a default gateway.
If you're not able to change the configuration of the DHCP server, you can make a note of the IP address and subnet mask given by the DHCP server (as seen in System Preferences > Network), and then disable DHCP on the Mac and send it to manual instead - entering the same IP address and subnet mask. Preferably you should then remove this particular address from the DHCP pool on the DHCP server so that it is not given to a different computer later.