nginx proxy manager crashes after reboot

[bbuster2]

When i restart the docker, nginx proxy manager starts and i can access the login. Also my hosts are up and running.
After a few minutes the proxy manager crashes. I cannot access Nginx proxy manager and my websites are offline.

I have checked the logs folder (/data/logs) but i don't see new error logs.

For example, i have restarted my server at 11:33 and this is the result:

root@nginx:/data/logs# ls -lt
total 6836
-rw-r--r-- 1 root root 1200013 Jan 12 11:34 proxy-host-2_access.log
-rw-r--r-- 1 root root 2031650 Jan 12 11:33 proxy-host-1_access.log
-rw-r--r-- 1 root root  308626 Jan 12 11:20 fallback_access.log
-rw-r--r-- 1 root root  281584 Jan 12 11:20 fallback_error.log
-rw-r--r-- 1 root root       0 Jan 12 11:11 proxy-host-2_error.log
-rw-r--r-- 1 root root  968093 Jan 12 11:04 proxy-host-7_access.log
-rw-r--r-- 1 root root   30416 Jan 12 10:57 proxy-host-1_error.log
-rw-r--r-- 1 root root     288 Jan 12 04:38 proxy-host-2_error.log.1.gz
-rw-r--r-- 1 root root   24245 Jan 11 11:55 proxy-host-7_error.log
-rw-r--r-- 1 root root  186293 Jan  6 23:58 proxy-host-1_access.log.1.gz
-rw-r--r-- 1 root root   76062 Jan  6 23:57 proxy-host-7_access.log.1.gz
-rw-r--r-- 1 root root   89511 Jan  6 23:57 proxy-host-2_access.log.1.gz
...
...

When manually starting nginx (with just the nginx command) it works and keeps working, but after a reboot, the same problem happens again.

Where can i start searching for a problem?

Update:
After rebooting the server, and checking the processes, i get this list:

root@nginx:~# pgrep -af 'nginx'
135 nginx: master process /usr/local/openresty/nginx/sbin/nginx -g daemon on; master_process on;
300 nginx: worker process                                                 
304 nginx: cache manager process                                          
305 nginx: cache loader process      

After half a minute with nginx still working:

root@nginx:~# pgrep -af 'nginx'
135 nginx: master process /usr/local/openresty/nginx/sbin/nginx -g daemon on; master_process on;
300 nginx: worker process                                                 
304 nginx: cache manager process  

After a few minutes with nginx crashed:

root@nginx:~# pgrep -af 'nginx'
root@nginx:~#