After installing a PowerLine adapter, the network connection from one server housing SQL Server (using SSMS) to another server (housing SQL Server) fails. The SQL server instances in question are not using hidden features (SQL Config mgr
= protocols, hidden instance) so the need to call them using the server name followed by comma followed by port number did not cross my mind (<servername.,<port>). Oddly, I even tried that and it still didn't connect.
I just set the port for the unreadchable sql server to be the same port as the one on the local box and it works. Connecting from the unreachable instance on its local to the one with the issue was never a problem. It was a one-way only situation.
My question is about the firewall settings. On both machines, I went the simplest route and enabled the sqlservr.exe (application) to have a firewall exception. None of this was a problem until I connected the upstairs to the downstairs with
a PowerLine adapter (in caps - it may be a bug in the company's product but I wish not to imply it is a device problem until there is more certainty).
I should mention that the downstairs connects from a modem to a router, to a managed switch (unmanaged at this time). The Powerline is connected to the downstairs switch. There is a second managed switch (currently unmanaged) that connects to
the powerline. Coming off there is a the connection to the sql server. Additionally, there is a second router which business computers connect to over a different NAT'd IP. I don't think any of this latter information is pertinent
but I include because with the PowerLine, the managed switches, and the additional router, and my experience as a layer 6 developer/dba and not as a layer 2/3 system administrator has me wondering where the problem actually lies.
I would bet on the firewall. But clearly I am out of my league. And relieved to finally, mysteriously, have it working again. All the machines are Windows 10 v.1809, or Windows 2016 (whatever the last update was).
R, J