1. From the main menu, select Play. 2. Go to the Servers tab. 3. Choose a featured server or click Add Server to enter the details (server name, address, port).
Biggest reason Splitscreen tends to not works is due to the Gamepad. You cannot do Splitscreen if player one is using the Gamepad. Try using an alternate.
Find a reliable server host, such as MCProHosting, and it will give you benefits of 24/7 access, modpacks, and more stability, as well as DDOS protection.