Limit of minimum upload speed can be very low even under 512 kb but it it is 512 kb upload set max players less only way to test online server get it much drivers and look at dedicated server how much % it have with 5 drivers or 50 on it
I have test edit the server settings a lot to try get max out of it.
Here is a multiplayer file that you lay in the userdata folder that you host server with copy your own multiplayer fil before you test this.
Edited Multiplayerfile 1.0
Edited Multiplayerfile so restarts have no delay (invisible cars on grid)
And server load game & tracks faster.
[ Multiplayer Server Options ]
(Edited)
Loading Sleep Time="2"
Loading Priority="2"
Wanna have more cars then mod allow.
(Edited)
Max MP Players="104"
If the upload drain your server so it lagg
(Edited)
Max Data Per Client="128"
Faster delay between sessions.
Allow Hotlap Completion="32" 32 means that hotlap is on warmup ! so 5 sec after P or Q time is on zero server shall chance to next session.
Delay Between Sessions="5.00000"
Delay After Race="20.00000"
This is minimum time i have test
IN PLR file you can set practice to 0 so server goes to qualify if you not wanna have practice .multiplayer file set password name ads as you want all this i set to ""
About host rfactor server everyone that want that is allowed to host servers.
A good prg to open ports for host rfactor i use this works great if you ar behind a router
http://www.simpleportforwarding.com/