It is a dynamic IP address and it was a power failure. I have heard that DynDNS.com is a good service to use. We lose power quite a bit where my vacation home is located, but usually for only a few minutes at a time, just enough time for the darn modem to obtain a new IP. Would it be smart to purchase a UPS for my modem, router, etc?
The biggest connectivity problem you are going to have is keeping track of the IP address of your vacation home. As others have mentioned most newer routers (DSL modems) have a dynamic dns client built it. The job of the client is update the ip addresss associated with a name of your choosing. So while your ip address might change, the dns name or url for accessing your vacation home wont change. The trick is to find that option in your router's configuration and see which dynamic dns providers it supports. dyndns.com is a fine example of such a provider. They have been around for a long time, offer a free service, and are quite likely supported by any router that supports dynamic dns.
The suggestion to use a vpn is not a bad one. However, configuring a vpn can be a real headache itself. First off, you are still going to have the problem of one end of the vpn finding the other end. This is the same problem as above. If your web browser cant find the remote machine, your vpn client wont be able to either. That said, I should also mention that there are "non-standard" vpn solutions such as hamachi that solve this problem without using dns. But these solutions have other limitations that a full blown vpn doesnt have.
Regardless, you cant go wrong by first setting up dynamic dns. If you understand port forwarding, you'll find that most of your remote connectivity problems can be solved with it. A properly set up vpn can be a wonderful thing mostly because of how flexible it is. It's just a big hammer for a small job.
If you can manage to leave a small computer running windows at your remote site, set it up for access via remote desktop and forward a port to it. You'll have even better access than a vpn will give you. You'll have a full desktop running inside your vacation home. Just connect to it whenever you need to check in on the Elk or any other home automation project you might have going. And all for the price of a single forwarded port.
As for the UPS question, sure. You're Elk doesnt really need it but it will probably lose it's network connection while the power is out because the M1XEP is usually not connected to the Elk's battery. Most power outages are pretty short so 20 minutes of UPS power will get you pretty far. DSL modems usually get a new ip address each time they boot up. The UPS will help to prevent some ip address changes. Even though you'll likely be using dynamic dns, this can still be a good thing. The only thing better than being able to re-establish a connection is not having too :wub: