Settings Lost After Power-Down

As Grizzly said, there is no reason the Linksys should drop its settings unless you have an issue with the Flash memory of the unit.

Is the unit still covered by warranty? If it is, I would RMA it, for a replacement.
The UPS is still a good idea also.

The key is: What does the OP really mean by loosing its settings. As previously said, when the power goes back on, both DHCP servers will allocate addresses, so it will probably not work.

Let's have the cable modem make & model, please.

I'm not sure we are talking about 2-NAT'ing here. One thing I know, though is that the OP said: "I have no idea what setup software is doing", when I do.
So I'd like more info to stop shooting in the dark

 
Grizzly>> "You should not have two DHCP servers on your network. It might work for a while, but you'll experience problems when leases are renewed (Like after a shutoff)."  
   
Avoiding the "double-DHCP" configuration seems like good advice.  I would think the prudent way to avoid "double-DHCP" would be to turn it off on the modem and assign a static IP to the "WAN side" of the Linksys router.  Agreed?    
   
MrJemson & Pugglewuggle>> Sounds like the router settings reside in flash memory or perhaps another variety of EEPROM that eventually loses its data when lacking a power source.  Here's the rub: The cable modem and Linksys router actually belong to some elderly friends who deliberately power down their entire office when they travel.  I omitted this fact in the original posting because the question was sufficiently complicated without it.  Despite my encouragement to do otherwise, they are going to continue to power down the office when they travel (which is often).  Additionally, they are not willing to manually set up the router after they return from their travels.  What I need is a router that holds onto its settings for an extended period of time.  Suggestions?  
   
Pugglewuggle>> "Also, try to avoid using the setup software - it is nothing but trouble. Just go to http://192.168.1.1 and setup the router from there when you first plug it in. The default username is blank and the password is "admin".  
   
I agree completely.  I'm not sure what to set up, however.  DHCP on both devices should take care of itself.  (Perhaps I simply have to activate it on the router?)  NAT (on the router) should take care of itself.  Maybe the "Internet Connection" (static or dynamic) type on the WAN side needs work?  In your experience, what settings need configuration on a Linksys router that is just out of the box?  
   
Pugglewuggle>> "One other thing - once you get your router configured, go to the Administration section. There is an option to backup the config. You can save it to a file on your PC. I recommend doing this so if the settings ever do get lost again you can just restore them in about 2 minutes."    
   
Very cool.  Do you need the setup software to run it from the PC, or is it a stand-alone executable?  

Pugglewuggle,

Wow, what a response.  I've incorporated both your responses into my personal network notes.  I posted another question on alternative router firmware.  I'd be interested in your take on it if you have a minute.

J