Picture a) tells me, something is wrong with your installation. It tells you that the game miss the Offline data. EDIT: please check content manager that these is installed ( fs-base-cgl ):
. It should normaly be present.
Picture b) you run into a network issue, and game switch to offline mode ( may be cause a) )
Picture c) is an annoying issue in MSFS : the validation of the input fields is some times realy worst for user experiance. Unfortunality you not show us what you try to enter. If you have trouble with these page the best is, to reset these whole settings-page to default.
The point b) ( going offline ) can have many reasons. As @Jigsaw407 mentioned the router or the whole connection ( from local LAN till router ) , or your ISP is blocking somewhat , DNS issues… .
But also the usage of a VPN, or as so often the usage of the google-maps-replacement-mod cause such trouble. And we should not forget the Anti-Virus tools and so on…