on my droplet all of sudden client live stream upload gets disconnected and later reconnected, and below error is fired...

It has NGINX RTMP Live Video Streaming. No PHP installed.

Error Log of RTMP at that time:

2018/03/23 22:02:22 [debug] 12805#0: *4 hls: update fragment
2018/03/23 22:02:22 [info] 12805#0: *1 recv() failed (104: Connection reset by peer), client: 36.255.234.243, server: 0.0.0.0:1935
2018/03/23 22:02:22 [info] 12805#0: *1 disconnect, client: 36.255.234.243, server: 0.0.0.0:1935
2018/03/23 22:02:22 [info] 12805#0: *1 deleteStream, client: 36.255.234.243, server: 0.0.0.0:1935

Is this error related to bandwidth port speed on my server or issue at my clients end?

This issue hapoens to 2 / 2 streams but not at same time.