Write speed slowing down to a crawl. Now what?

I’m running my MBLD 4 TB as JBOD at capacity (20 GB left). Might this be the reason I’m not getting more than 5 MB/s write speed no matter if over network or from attached USB drive? Read speed over network is at 30 MB/s.

Hi Techflaws, I also have a MBLD 4 TB as JBOD, but with 2TB free. My write speed over the network is 15/20 MB/s.