The server is not crashing due to the forge version. It says
| [13:08:05] [Aternos System/ERROR] [LOG]: Server was stopped because it took too long to start. Try reducing the load to avoid this in the future. |
It looks like the Aternos system system stopped your server because it took too long for it to start. This can happen when a server is overloaded (too many plugins, resource-heavy modpack, etc.). The Aternos system automatically stops servers if they don't respond within a certain amount of time to prevent them from getting stuck during startup. Especially in the afternoon (Central European Time), when many servers run simultaneously, servers running many mods sometimes take too long to start.
Unfortunately, there is not much that can be done about this. You can only try to start your server again at another time, remove some resources (e.g. plugins/mods).