Few tips from me,
I can't say that i know everything, i get many troubles even on my server season2,
But when someone open a server he must be aware of many things and much more when you have to make big changes or even upgrade versions,
There is also many parameters about your hosting computers, your networks, OS , files , attacks and much more.
Mu Online generally is not created with the best specifications at all, some people try hard to make the best out there, i know the money you have to spend are not few bucks but there are many reasons why require more money. I had a Season2 server which one could give me enough money to spend my Month plus servers needs, i don't see any reason why a Season9 server can't do this to you, i bet is Administrators fault.
First of all you must Search around you, what is the best option you have to make the best or a good server, how it can give you more money how many similar server is out there and much more.. The best promotion of your server and the best quality, clean head to fix and take care of all things. My personal advice is : Learn every day more about Mu (if you wanna make a good and stable server) check each online server if you can, find mistakes/ wrongconfigurations on other servers so you will be prepared in any case.
Suddenly success is not for everyone but with good effort and hard work, anything is possible.