Following the README for the ASL image: http://dvswitch.org/files/ASL_Images/Raspberry_Pi/Stretch/ASL_1.01-20180228-armhf-raspbian-stretch-image.readme
and it advises to hold two kernel packages which have succeeded but then running
apt update fails with all three package repository links not found.
Is there a more up-to-date image? Are there alternate package repositories?
I am a long time Debian (and by extension Raspbian) user and am familiar with the apt system.