OK so the Netgear GS748T switch was delivered and is junk! First thing I noticed was a badly twisted mount ear. Plugging it in resulted in the fans sounding like they were being feed an iron bar. Closer inspection found 2 fans were almost dead and grinding while slowly turning and the 3rd was grinding very loudly as it turned at various speeds. Fans are easy enough to replace so I moved on to test ports. Using new Cat6a cables I plugged its Port1 into my main switch, used Netgear's Smartwizard Discovery software from my desktop to find and assign an IP then pulled up the web interface... all good. Plugged a laptop into port 3 (static 192.168.1.245) and another into port 48 (192.168.1.58 via DHCP). From the laptop in port 48 I used "ping -t 192.168.1.245" got a couple replies, unplugged from port3 and into port5, etc along the top row. At port39 it failed to reply though link/speed leds lit up. OK 1 bad port.. bummer. Continuing on more and more started to fail. Switched out the laptop on port 48 to see if that port was failing however it didn't help. Pulled the switch - switch from port1 and inserted it into port39 and I could no longer pullup the web interface. Switched out cables and tested two more ports on the off chance and, as I knew, still no go. As I placed my hand on the top it was noticeably hot, far more then it should have been. Pulled power, disconnected laptops, cables, fired the thing back into the shipping box and emailed the seller.
Reminded me why I rarely order 2nd hand equipment!