Cannot start server with Ethernet cable connection

So as the title says, my friend cannot start the server. We live in a dormitory so we cannot affect the router. And he uses the cable connection. At the beginning it didn't work and we didn't know why. After some time it started to work, so we could play. And now the issue is the same. When his pc is a hotspot (to which I connect my laptop) i CAN start the server. The server starts with using mobile data as well. But it DOES NOT when the cable is used. We really have no clue what's going on. But here's the error he got when tried to start the server using .bat file.