Network speed unstable when access to file on network drive using SMB

Hello Everyone,

I have a big problem and need your guidance.

I have a Synology NAS (SMB Server) and one windows server 2016 (SMB client). I created two shared folders and map them into the windows server. On win server 2016, I installed CCTV software and using two share folders to contain camera data.

But, I found an issue. When I access the shared folder via windows explorer the network speed on my server becomes unstable (you can see in the image I attached)

Please let me ask has anyone ever encountered this case? and why did this problem occur when using SMB Protocol?