After a search and test, it is the SSL certificate that seems to be causing the problem.
Changing the line in this file: /etc/systemd/system/novnc.service
ExecStart=/opt/noVNC/utils/launch.sh --listen 443 --ssl-only --vnc localhost:5900 > /dev/null 2>&1
to
ExecStart=/opt/noVNC/utils/launch.sh --listen 5050 --vnc localhost:5900 > /dev/null 2>&1
astroberry.local:5050/ definitely allows things to work. Unfortunately the SSL is lost.
This page suggests a correction:
github.com/novnc/websockify/wiki/Encrypted-Connections
Extracting the CERTIFICATE from /opt/noVNC/self.pem and putting it into a self.cer file does create a certificate that can be imported into iOS, by emailing to myself.
The common name is astroberry.local is different than the hostname astroberry. Putting the CER file on iOS still did not allow for the SSL log in. Perhaps it is the .local?
Perhaps a web page on astroberry that can allow for the download of the public certificate so it can be install on iOS can work. Just a thought.
I can test again tomorrow.