Install a More Animals [FORGE] - 1.21 UPDATE! server through the Control Panel (Servers → Select your server → Game servers → Add Game Server → More Animals [FORGE] - 1.21 UPDATE!)
I run a highly complex and large modded Minecraft for me and my friend, easy to use, very good uptime, and minimal to no lag, with a 1200 mod world!!
I would highly reccomend this to anyone!