Requires a minimum of 3 servers:

1. Proxy (Bungeecord)
2. Hub
3. Server (survival, skywars, etc...)

If you want a 3 server network for example, skyblock, survival and skywars, it would be like this:

1. Proxy (Bungeecord)
2. Hub
3. SkyBlock
4. Survival
5. SkyWars