Yes a dedicated server is not cheap. It starts from around 10,- €/month but, like Denstjiro said, that will not be good enough for rfactor to run in a satisfying way.
I think you will have to pay ~ 40,-/50,- € for a good one, depending of what hardware and other things (traffic-flatrate...) you want to have.
(We for example pay 60,-/month for our server we use for rfactor and our website)
But back to the current problem.
The control panel you use to manage the server.
How is it working?
Do you have all possibilities in setting the options as the rfactor dedicated has?
And if yes, when you stop it, upload your track and start the settings-procedure, can you select the uploaded track?
If yes, is the choosen track correctly shown in the rfactor lobby?