Hey! Guess what?!?
I'm NOT posting a Technical
QUESTION about a problem I had, I'm posting
AN ANSWER to a problem I had!
Last night, just as I was going to bed (2AM PST), son seeks me out and mentions that "the network is down."
I spend a good half-hour trying to hunt things down, but am stumped by conditions that I've never seen before:
One of my routers (on one of my subnets, the main household one) seems to be acting LIKE A SWITCH!?!All the IP addresses that I get from it are in the wrong subnetwork! (They're from one level down....)
I give up, tell him "Tough luck for you and your Late-Night 'run & gun' playmates. I'll look at it tomorrow..."
So this morning I pull out the router and take it to my test bench with all its "
spare parts*."
...Everything works fine.
So I take it back to it's spot and plug it in, and notice something: The front lights aren't displaying as they did on the bench. They're not correct. Instead of showing connection for the WAN and the one LAN connection - as it showed at the bench testing correctly, ALL the lights are light, and are staying lit continuously!
BOY am I glad that I noticed that difference!!! ... Because it gave me a "EUREKA" moment that would have taken HOURS more to figure out!:
The wall-wart had gone bad! (The modular power supply transformer/electrical cord combo thingy.)
I had NOT taken the in-place power device with me for testing, and instead used the still-new one that was in the "parts" box!
Sure enough, when I replaced the "bad" one with the spare...
VOILA! Everything was fine again! I'm back in multi-subnet heaven again!
So the reason I'm posting this story here is to share my new-found lesson with y'all: 
When investigating a failed electronic device ALWAYS CONSIDER THE POWER SOURCE as a potential source of the problem too! (Even/ESPECIALLY when it seems IMPOSSIBLE to cause THAT kind of problem!) 
* 
When I buy a router that I like/meets my needs well, I always BUY TWO OF THEM so I have "parts" to keep it going for a long time. Right now I'm actually on the "replacement" (last chance) router itself, as the original one worked for 6 years and finally died this past April....
