the hash on the end of the room name is your IP Address (and the port the channel is on) - you are obviously using a connection with a dynamic IP Address that changes every time you connect and also using a modem connected directly to the computer, the only solution is either to get a static IP Address from your ISP (which would cost extra, and in most cases require a "business" connection as well as the extra "static IP" fee) or buy a router and keep it online all of the time so it maintains the connection 24 hours a day (so even if your computer is off the router stays connected to your ISP so doesn't need to change IP Address)
there is no simple setting you can change as it is not something determined by your computer but by your ISP, and there isn't anything you can do about it from your end
