Multiplayer in Eaglercraft relies on WebSockets ( wss:// ). You cannot connect directly to standard Java servers unless those servers run a WebSocket-to-TCP proxy, like an EaglercraftXBungee plugin. To Join a Multiplayer Server:
The "work" behind the Eaglercraft 1.8.8 client is not a simple re-skin but a complete re-engineering of the Minecraft client backend. eaglercraft 188 client work
Eaglercraft uses ws:// or wss:// WebSocket addresses, not IP:port like Java Edition. Multiplayer in Eaglercraft relies on WebSockets ( wss:// )