syncing disk, buffer remaining...

[nukem]

hi friends { sorry for poor English :) }
as you can see in the attached images, there is a problem in our firewall.
notes:

• if up time be few days long syncing will be much longer
  -dashboard page take a long time to load and some time 504 Gateway Time-out (nginx) occurred.
  -2.4.4-RELEASE-p2 (amd64) /FreeBSD 11.2-RELEASE-p6
  -Intel(R) Core(TM) i3 CPU 540 @ 3.07GHz 4 CPUs: 1 package(s) x 2 core(s) x 2
  hardware threads
• 4 GB Ram
  -Sata H.D.D
  
  Regards

[jimp]

That is likely either a filesystem issue or an issue with the disk itself.

First thing to do is boot it into single user mode and run fsck -y / a few times until it doesn't find any problems or fix any problems.

If that is all clean and the problem persists, try running a SMART test on the disk to see if anything turns up.