Video Files Won't Upload in 1.7.9

I’ve been running a 1.7.9 server for several years and routinely upload video files (mp4) for display on the system. The sever now won’t accept any file larger than 13M (size limit is default 128M) and randomly names files 13M or smaller. The server continues to function fine in all other respects. I’ve changed nothing with the software or on the hosted server it runs upon. Server has plenty of space. I’ve run the diagnostics procedure from the dashboard, but this forum will not allow me to upload it. Accordingly, I’ve posted it to One Drive:!Agy1s40VI9-dhaFDuFsZpOENyrKECQ. Thanks in advance for any suggestions.