GS324-100NAS Lights On but nothing works

Just like another post from last year  with almost identical subject line!

In my case, the switch seemed to work fine for 3 months. Busy Office network with VOIP phones and 12 PCs and a few printers.

Then it totally stopped routing ANY traffic. Like its unplugged.

Except, its not unplugged; all the link lights are on and blinking like everything is A-OK. I cycled power to it several times. Each time the traffic LEDs come on and twinkle normally, but not a single packet gets routed.

Since it had to be either this switch or the Network cable linking it to the Internet modem, I swapped out the switch with a 15 year old TP Link switch, and everything came back up!

Is there something I can fix here, or is it RMA time?

Thanks in advance.