I've been checking the router and for now it is stable except the total available ram decreases on LuCI.
Today, it is at 8.86mb, a few days ago it was roughly ~ 10-11mb.
I've tried to find if there was a memory leak, but found nothing wrong.
Strangely, when using free or top, it doesn't seems to be calculated like LuCI ?
Will the router do a memory issue after some time or it looks to be stable ?
Things can be cached/buffered to increase efficiency. This will reduce the available memory. When needed the memory can be claimed back. You can clean the page cache manually with sync; echo 1 > /proc/sys/vm/drop_caches
I'll just do this when the memory available is lower than ~5 mb just in case.
If it goes to 0mb, would it do some issues or it is an expected behavior ?
If some application requires more memory, the buffered/cached will be purged automatically.
You could run it as cronjob daily if it makes you feel better, or you can forget it.