Question: Running Obsolete Airport on High Sierra
I still own and use the very 1st Airport Extreme (flying saucer with dome). I've always managed to keep everything going through the numerous upgrades with the help of contributors far more knowledgeable than myself.
After upgrading today to High Sierra I realized I was no longer able to manage Airport Extreme although I could sign into the network and it performed properly otherwise. I went to the website of the well known advocate for these devices, downloaded and installed the .dmg file - no change. Downloaded and installed the .zip file over top of the .dmg file and presto! 5.6.1 opens and I can manage my wireless networks.
Patience is a virtue.
iMac (21.5-inch, Late 2013), macOS High Sierra (10.13.1), 15 inch MBP (late 2013)