Struggling With Low Speeds < 15MBps Over Gigabit

The ping test shows that your network doesn't carry jumbo frames. In fact, you are not getting the normal ethernet MTU of 1500 - you start running into problems at 1490 or larger. (you add 40 bytes to the ping value you found to get the max frame size).

You did test this over ethernet correct? WiFi doesn't carry jumbo frames.

So I suggest turning jumbo frames off for now, and reduce the frame size to 1480, and retest. Packet fragmentation will certainly reduce throughput.

Then try to figure out what component is interfering with the jumbo frames. If all your devices are connected to the trendnet switch, then it is not router. If you have devices connected to the router,try moving them to the switch (as most consumer routers do NOT support jumbo frames).

On the disks, I'm not sure what the program fail cnt is about, but the other parameters look fine. The program fail cnt is Samsung specific, none of my disks source that parameter.