Nginx "address already in use" when installing and 403 Forbidden (Ender-3 V3 KE)

[g1sbi]

When installing nginx, the procedure goes smoothly until the end, where I get:

Info: Starting Nginx service...
Starting nginx...
nginx: [emerg] bind() to 0.0.0.0:4408 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4409 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4408 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4409 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4408 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4409 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4408 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4409 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4408 failed (125: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:4409 failed (125: Address already in use)
nginx: [emerg] still could not bind()
Info: Starting Moonraker service...

System data

     System: Linux (Kernel 4.4.94)                           
 │    Firmware: V1.1.0.15                                       
 │    Hostname: F005-5CE2                                       
 │   Device SN: 92995711035CE2                                  
 │  IP Address: 192.168.3.104 (WLAN)                            
 │ MAC Address: FC:EE:11:03:5C:E2                               
 │   RAM Usage: 67 MB / 197 MB (34% available)                  
 │  Disk Usage: 1.8G / 5.9G (3.8G available)                    
 │      Uptime: 0 days 1 hours 10 minutes                       
 │   Processes: 94 running process                              
 │ System Load: 0.21 (1 min.) / 0.47 (5 min.) / 0.50 (15 min.)

I don't really know what could be causing this on my network. How can I troubleshoot this?

[g1sbi]

SOLVED

The old process was still hanging in there, even after uninstalling. Running lsof | grep nginx yielded the processes to kill.

After that, I was still getting 403 Forbidden, which I fixed thanks to this discussion: #459