Add a server IP manually. Note: Some servers block Shadow Client. Test on open servers like pvp.eaglercraft.gg or eaglercraft.org . If you get kicked, the server has anti-cheat detection.
Use a "Lite" version of Shadow Client that includes only performance and cosmetic mods. Disable all PvP cheats (aim assist, reach, velocity) unless playing on a server that explicitly allows them (e.g., "anarchy" or "cheat-friendly" servers). shadow client eaglercraft