there are many more packs in the asset store for network functionality. e.g. Photon.
They mostly use a similar sales model… you get X number of “Free” concurrent users… (for development & testing) but you need to pay to use their services (code / servers / bandwidth) once you have a lot of players. The cost scales up and down with number of players.
Or you host your own server, with your own code.
Or see if anyone released a free network solution, you still need to provide some servers of figure out the hosting)
Note:- those paid solutions are generally very cheap for only a few players… if you have a lot of (paying) players then you don’t need to worry cost.