100MB upload in 2018?
I'm using this formula and is great:
OVH (Cloud VPS / Linux 64b / 4GB RAM / 1Core / 40GB SSD / 100Mb up and down) + approx. 7-8 Euro /month = approx. 350 online players.

Is working only with L2J servers till H5 (not with shitty aCis or L2J H5)
For servers like L2J H5, L2J Unity Grand Crusade and IL aCis you'll need VPS with at least 8 GB RAM or a dedicated machine (but expensive)
About your hardware..
Most important thing is your bandwith if you have 1GB connection then you can use shitty server as Core2Duo and any 64b Linux OS and a lot of RAM lol.