How do I connect my Time Capsule as a NAS to an existing network?

Question

NAS

Friends, tired of fighting. There is an old Time Capsule. There is Internet via optics from MGTS, with its own router, of course. How to connect the Time Capsule to the current network over the air to use the vehicle as a NAS? Everything works fine on the Ethernet. If the HARDWARE acts itself, as a router - too. But the required configuration does not start.