Maybe it helps someone else :-)
We did a do-release-upgrade to Ubuntu LTS 20.04 and thereby broke APN
Jamf was very helpful in pointing out that you need a missing cert:
cd /usr/local/share/ca-certificates
sudo wget https://www.geotrust.com/resources/root_certificates/certificates/GeoTrust_Global_CA.pem
sudo mv GeoTrust_Global_CA.pem GeoTrust_Global_CA.crt
sudo update-ca-certificates
reboot
Thanks again for the great support
