Hi Mary,
If it says "authentication not found", you could try re-entering your EchoLink credentials into RepeaterPhone; I've had a couple people with situations where RP somehow forgot their saved credentials.
When it says "Node Offline", this is based on the most recent directory listing from the EchoLink servers. If you feel like it's out of date, you can pull down on the directory listing to refresh the list.
When you say someone can access the node via "other means", does this mean RF? or a different EchoLink app? If it's via RF, remember that for EchoLink to work, it needs an active Internet connection. If something has been interrupted, you'll still be able to access it from a radio but not via the Internet.
Another possibility is that some of these EchoLink nodes may not have "Allow Conferences" turned on or may have the conference limit set to a low number. For example, there is a repeater in a town near me that has an EchoLink computer connected, but "Allow Conferences" is disabled. This means that only one person can connect at a time.
- Wes W8WJB