When I installed naviserver and openacs I used the installation scripts (https://openacs.org/xowiki/naviserver-openacs).
On Debian 9 I followed these instructions:
cd /usr/local/src
git clone https://github.com/gustafn/install-ns
cd install-ns
sudo bash
bash install-ns.sh
bash install-ns.sh build
bash install-oacs.sh
bash install-oacs.sh build
After this, openacs started with the config.tcl file from the naviserver directory and /lib/systemd/system/example.service also used it:
/usr/local/ns/config-example.tcl
On openacs I ran letsencrypt (/var/www/example/packages/acs-subsite/www/admin/letsencrypt.tcl) from http://example.com/admin/letsencrypt. On successful completion, /usr/local/ns/config-example.tcl was automatically updated to point to the new certificate.
Since then, I have been using /user/local/ns/config-example.tcl. Based on your reply I updated this file and am now able to see the values of the bind variables. Next I will move everything over to use /var/www/example/etc/config.tcl.
Thank you for your help