I know this is a old thread, however I have some information that might help you.  I had a few miners that I purchased online and had similar issues.. This is what I found,  The connection you have "192.169.6.241"  is not needed for the miner and its a botnet/bittorrent connection.. you can google port 48748 to see what I am referring to.   I was able to wireshark the connection and noticed this would connect after about 15 minutes after first boot. This is using sshd2 to make a secure connection to 192.169.6.241   (note this looks deceiving cause most private networks are on 192.168.X).

To remove this, I reset ant miner S9 to factory defaults, then flashed latest Bitmain S9 JULY 2019 (NOTE THIS CLOSES SSH "USE CAUTION) and then setup worker pool, no issues.

(2) Option go into your router and block in/out traffic for  destination 192.169.6.0/24 or 192.169.6.0-192.168.6.254

Also did you ever load non stock firmware on these miners?

Hope that helps
LP