Thanks Elden. When you posted this message, I had already been working on that feature, and it's done and pushed up into the master branch, ready for you to pull down.
An intelligent last heard list requires a database and based on QnetGatway's modest needs, I chose Sqlite3. Before you make the new programs, you'll need an Sqlite3 development package:
sudo apt install libsqlite3-dev
You can use the qnadmin script to rebuild your code, or do it with make commands and the start and stop aliases, if you installed those. Also uninstall the php server (sudo make uninstalldash) and reinstall it (sudo make installdash) as you will also need some php-sqlite3 packages and this will get them installed.
Be sure to look at the DASHBOARD.README file as well. You can turn off any section of the dashboard you want. You do this in qnconfig and these changes should be seen on your dashboard as soon as you write out the qn.cfg file.
Callsigns in the Last Heard are linked to the QRZ database. Here is what the dashboard looks like with the Last Heard section (hiding the IP Addresses section):
Tom Early