Re: Switches suddenly won't connect to FiOS router (M124-WR)
Sounds like a bad switch to me. Unfortunately, it's not rare at all. Certain revisions Netgear ProSafe switches are known for failing capacitors causing them to die prematurely. More recent ProSafe switches have a lifetime warranty, so you may have some luck getting Netgear to replace it. They can also be repaired pretty easily if you know what you're doing with a soldering iron. When you swapped out the 16 port vs 5 port switch, did you use the same power supply? I've seen the power supplies for switches fail as well, and if you used the same bad supply with both switches it could explain why they both appeared to be bad.
Did you use the same ethernet cable for the two different switches. Are you using an old crossover ethernet cable or a port marked uplink? I am not familiar with these switches. I have an 8 port linksys plugged into my router with no problems. Try o isolate the fault down to one component.