Router, ups and strange behaviour


Regular Contributor
Just an observation, maybe reported before; if so, I apologize for the noise. However, just in case it might help someone:

It seems as if it would be a good idea to put router, switch, isp modem etc on an ups. I had an unused older spare
lying around so I used that.

A day or so later, seemingly out of the blue, I started to get weird connectivity issues such as gui logins not recognizing passwords,
captchas, router reported connected but can’t access website(s), and other strange “unknown cause” behaviour such as has been
reported with puzzlement here from time to time.

I also noticed that the wall warts for the router and switch and also the isp modem itself were running noticeably
hot to the touch. So I reverted to connecting the gear directly to the wall plug.

A day later and the stuff is all running cool and no more unusual router etc. weirdness has been noticed. My guess
would be that some of the gear was somewhat unhappy with a modified square wave.

Or maybe none of this has anything to do with anything.

Lotta Cox

Senior Member
The UPS will only output a simulated sine wave when there is a power loss.
Get a different UPS.
My AC86U runs fine on modified square waves when the power is out. Same with cable modem.


Very Senior Member
It has been at least 2 decades since I've run equipment without a UPS (APC is my typical choice). I run 4 of them to cover various routers, switches, phones, TV, etc. Never had an issues with "standby" or "hot" conditioning personally. Good that you were monitoring your situation, but it sounds fairly rare and more of an issue specific to the brand or model you have.


Regular Contributor
The UPS will only output a simulated sine wave when there is a power loss.
Good point. Though it seems possible that this particular ups didn't read the spec sheet very well. And yes, that specific ups is headed for the exit soonest.

My point in posting the observation was simply to suggest, especially to other people seeing router weirdness and the like, that the real cause of said weirdness might not be the obvious suspect.

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