If you are using mods, and the server will not start, it is most likely a broken mod, or maybe one of your mods need a support mod. To fix a modded server not starting, you are able to check your logs if there is a broken mod. After that, you have to delete that particular mod. But, if you are using a modpack, there is not much you can do because you cannot delete a separate mod in the modpack.
A mod or modpack may run fine when you started to use it. But, it is able to break at any time. Some may not start, cause the more you use it, so the more RAM you need. Besides, because Aternos has a RAM limit, eventually it is going to give up and start to crash. We suggest you trying to get the best possible balance between the limited resources and the best performance. Especially for modpacks, we think that it is really hard to achieve. The team of Aternos test the modpacks in their system to make sure that they are at least starting and that basic playing is possible. As modpacks are always a bit different and the load on their host systems is also always different, so they cannot guarantee anything. However, they decided to still offer modpacks on their platform because they want to offer as many as possible options to customize your server.
Now, you may want to know how to check your server log. For your information, the best source to find problems with your server is the log file. You will be able to access here: https://aternos.org/log/. To identify something wrong with your server, you will most likely look for the errors that you are able to find in lines with the Error log level.
Sometimes the surrounding lines of an error provide further information about the error, so reading them might help. In this case, if you do not understand the error message, you are able to try to google it to see if other servers had similar issues. When there are any suggestions available, you are going to see them at the top of the page. You will get automatic suggestions for errors in your log and buttons on how to fix those errors. Please follow those suggestions to fix your problem.
If you still have the problems starting your server, you are able to open a ticket. Please ensure to include details as many as possible and also include the link to your log on mclo.gs. For your information, mclo.gs is a site developed by Aternos for simple log sharing, reading and analysing. You have to go to your log in the Aternos panel and click on the button “Share” in the top right. Then, you will get a field with the link to your log on mclo.gs. Reading a log is not easy, but learning it helps to identify the issues with your server easier and faster.
