Who is this that keeps trying to connect to Blue iris ???

zg-0517a-52.stetchoid.com

Who / what is "zg-0517a-52.stetchoid.com"

I believe it's "stretchoid" with an 'r'. Port scanners hosted on Digital Ocean, looking for vulnerabilities. I advise you to NOT go to their dot-com and submit 'Opt Out', it just gathers more info from you. More reading here.
 
Thank you sir. The last attempt came from a local computer running Linux (Mint - MATE). Could it be infected with a virus?
Not sure. Could be a bot from someone's already hacked cam or router with forwarded ports or UPnP wide open!
As if day-to-day life isn't already a struggle, one has to be on constant patrol for these cockroaches. I wouldn't lose a wink of sleep if one day someone actually caught one red-handed and took them for a little midnight ride in the countryside......but that's just me.