Original User: kmjohnsonOk, seems I've found the answer to my own question here. So I will post it in case it helps anyone else out.I used this URL to connect via "Add ArcGIS Server" in ArcMap: http://ctecoapp3.uconn.edu/arcgis/services. This connection allowed me to connect to all of the layers made available via that server.In ArcGIS Online, it appears that I can only add the layers via that server one at a time. So I had to locate the section on their website where they listed the available layers, and add them one at a time via the "Add Item" in the "My Content" section of ArcGIS online.The individual layers could be added once a folder and service name were available (in the below URL, the folder is "images", the service name is "ortho_2012" and the type is ImageServer). So an example of one layer would be:http://www.ctecoapp3.uconn.edu/arcgis/rest/services/images/ortho_2012/ImageServerHope that might help anyone else with the same issue.