And Barone wasn't exaggerating when he said it was hidden. To access the mobile version of the game's title screen, players must perform a sequence of taps on specific sheets in the Stardew Valley logo, then press a different button. (You can find the detailed steps on the game website or paste them below.) Doing this correctly will add a co-op button to the title screen. Barone said mobile multiplayer works “pretty much the same as it does on other platforms,” except there's no way to “discover” other people's farms. You can only connect through IP addresses, he said, so you must use the same local network or create an access point.
Barone said the ideal way to use mobile multiplayer is to host a farm on a Windows PC and then access that farm through the mobile device using the same IP address, over Wi-Fi. Barone said the worst-case scenario is probably connecting to a farm hosted by someone using a hotspot that everyone can connect to; The app can be “interrupted repeatedly” by missing service points or calls, making the experience frustrating.
“However, if you want to try these things, nothing will stop you,” Barone wrote. “Just keep in mind that inherent connectivity issues may arise when trying to host a multiplayer game from a mobile device.”
If you're looking to access multiplayer on your mobile device, here's how to do it, right from Stardew ValleyWebsite of:
For iOS: Settings -> Wi-Fi -> Click (i) next to your Wi-Fi name -> Find “IP Address”
For Android: Settings -> Network & Internet -> Internet -> Click the gear next to your Wi-Fi name -> Search for “IP address”