It was very interesting problem. I met this problem too. With a lot of trying I've just solved this problem. The main issue is that can't excute command. If you replace ExecStart line with this ExecStart=/bin/bash -c "source /home/ubuntu/.nvm/nvm.sh && /home/ubuntu/.nvm/versions/node/v22.11.0/bin/http-server -p 8080", you can fix this issue. Thank you.