slow WAN transfer

[animefans]

Not sure if this is due to older version of omnios, or just some configuration issue

nappit rsync from WAN to local (~800Kb/s)

operator@nappit:/zpool1/Media/Video$ rsync -av -e 'ssh -p XXXX' --info=progress2 deb***@x.x.x.:/tmp/video.mp4 /zpool1/Media/Video
deb***@x.x.x.x's password:
receiving incremental file list
video.mp4
    258,677,397 100%  787.51kB/s    0:05:20 (xfr#1, to-chk=0/1)

sent 43 bytes  received 258,740,674 bytes  771,209.29 bytes/sec
total size is 258,677,397  speedup is 1.00

debian rsync from WAN to local (~10MB/s)

kkfong@cudabian:~$ rsync -av -e 'ssh -p XXXX' --info=progress2 deb***@x.x.x.x:/tmp/video.mp4 /tmp
deb***@x.x.x.x's password:
receiving incremental file list
video.mp4
    258,677,397 100%    9.52MB/s    0:00:25 (xfr#1, to-chk=0/1)

sent 43 bytes  received 258,740,674 bytes  6,550,397.90 bytes/sec
total size is 258,677,397  speedup is 1.00

nappit rsync from WAN to local (~800Kb/s as well to a different remote host)

rsync -av --info=progress2 k****g@x.y.com:/media/x/y/z/data/123.mkv /zpool1/Media/Video/
k****g@x.y.com's password:
receiving incremental file list
123.mkv
     67,731,062 100%  742.59kB/s    0:01:29 (xfr#1, to-chk=0/1)

sent 43 bytes  received 67,747,696 bytes  694,848.61 bytes/sec
total size is 67,731,062  speedup is 1.00

nappit rsync from local to local. bandwidth is as expected

operator@nappit:/zpool1/Media/Video$ rsync -av --info=progress2 kkfong@cudabian:/tmp/video.mp4 /tmp
kkfong@cudabian's password:
receiving incremental file list
video.mp4
    258,677,397 100%  109.01MB/s    0:00:02 (xfr#1, to-chk=0/1)

sent 43 bytes  received 258,740,658 bytes  30,440,082.47 bytes/sec
total size is 258,677,397  speedup is 1.00

any idea why nappit WAN transfer speed is so slow?