Thanks for your help.
The problem is that the server starts, but joining is not possible. After running for a few minutes it crashes due to an out of memory error. The server isn't running on 12GB the whole time. It starts on few hundred megabytes and climbs up to 12 GB or more depending how much I allocate. The minimum RAM is set to 128 megabytes.
Here's a link to the debug.log:
https://icedrive.net/s/kkf6t9TtCaZ5W556X9vB5k3atizi
Could dynmap and dynmapblockscan be a part of the problem?
Thanks
P.S. i downloaded the mods onto my Computer and there persists the same.