I think I solved it by adding the required domains and URL’s to a custom Whitelist.
This thread gave me the idea.
Create a custom template fragment:
mkdir -p /etc/e-smith/templates-custom/etc/c-icap/c-icap.conf
Create a custom fragment file:
nano /etc/e-smith/templates-custom/etc/c-icap/c-icap.conf/90custom_whitelist
Add your whitelist entries (without spaces):
####### Custom whitelist entries
WhitelistDomain \ .example\ .comWhitelistURL http://100\ .0\ .0\ .1
WhitelistURL https://100\ .0\ .0\ .1
Expand the template:
signal-event nethserver-squidguard-update
Restart and enable the relevant services:
systemctl restart c-icap
systemctl enable c-icap
systemctl restart squid
Tomorrow I will test it some more.
Please advice and comment.