GS324TP upstream port deactivates

Hello Everyone,  

   I have had a GS324TP 24 port smarth switch (POE+) for a couple years now.  No problems with it until last couple of months.  Now, the upstream port connected to my router will randonly die after a random period of time anywayre where 1 hour to a few weeks.  I can switch to a new port and it will work again for a while, then switch to a second new port and it will continue to work some more for a while.   I can keep repeating this until all of the available ports are used up.  If I restart/factory reset the switch all the ports are active again for while.  

I have read some other articles suggest that it could be the switch deactivating the port becuase of a DOS attack.  However, I am not sure how to confirm this and then solve it without a restart.

The included pic shows several of the ports that have have failed one after another.