From the Super Mario Wiki
The Retro Router is a large, mechanical device that appeared in The Super Mario Bros. Super Show! episode "The Adventures of Sherlock Mario". Despite the name, the Retro Router is nothing like an actual router. This episode featured Professor Kooparity and the Koopa Pack stealing it and attempting to use it to flood the city of Victoria.
According to Herlock Solmes, the world's greatest detective, the Retro Router is a weapon, though who invented the Retro Router is left unexplained by Herlock Solmes. Apparently, the Retro Router was created to flood areas by being connected to that area's sewer system, which would allow the Retro Router to pump vast amounts of water up above. Before it was stolen and subsequently, accidentally, destroyed by Professor Kooparity, the Retro Router was kept in the Tower of Victoria, in a small cell behind several metal bars.