I've configured a popup for PLSS townships to show a hyperlink for an ftp server with files organized by township.
When I click the link in the AGOL map viewer on a desktop browser (chrome) the link works fine. If I click the link while viewing the map in a web app the link results in a garbage url and fails. When I test this on an android tablet neither the map viewer not the web app work.
I've following the following blog to create my link structure:
Using URL parameters in pop-ups | ArcGIS Blog
a typical url looks as such:
ftp://999.9.9.999/CORNER RECORDATIONS/T{township} R{range}
the garbage url adds the address of the map or app before the link and looks like this:
http://<organization>/apps/webappviewer/index.html?id=<app id>#999.9.9.999/CORNER RECORDATIONS/T{township} R{range}
Based on the blog comments this happened to other people as well, but the problem either disappeared magically or was given up on.