When renting a Minecraft server, this is the default commandline as shown below. The commandline is intended for Minecraft Vanilla only but may work with the mods you are installing for a short time. 

Therefor we recommend taking some intel before using the the built in commandline. if any reason the command line needs to be edited, you can always make an custom commandline by yourself.

"-Xmx![Xmx]M -Xms![Xms]M -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -jar minecraft_server.jar nogui"

If you are stuck with your commandline not working or your server is not starting, please check the commandline as far as we know this commandline suits best for the original version of Minecraft Vanilla. 

How can i change commandline?

To change commandline all you need to do is go to your game server and click on "Commandline Manager" -> "Custom Commandlines" 

from there you can see a plus(+) icon with a text named "New", Click on it. You should then see this as in the image below:

Make sure you Tick the boxes on the left before saving. Unticked means not Enabled and Unticked means Disabled.

For a list of Command lines we recommend do your own research, if you need any help our support is available to support you 24/7 and 365 days a year!

Cheers, Kev