Now after all this, I wanted to do a restore of PiHole, but it tells me that FLT is not installed and that it is not enabled to download the latest version of the software.
pihole -r
[✓] Root user check
.;;,.
.ccccc:,.
:cccclll:. ..,,
:ccccclll. ;ooodc
'ccll:;ll .oooodc
.;cll.;;looo:.
.. ','.
.',,,,,,'.
.',,,,,,,,,,.
.',,,,,,,,,,,,....
....''',,,,,,,'.......
......... .... .........
.......... ..........
.......... ..........
......... .... .........
........,,,,,,,'......
....',,,,,,,,,,,,.
.',,,,,,,,,'.
.',,,,,,'.
..'''.
[i] Existing PHP installation detected : PHP version 7.0.33-0+deb9u1
[i] Repair option selected
[✓] Disk space check
[✓] Update local cache of available packages
[✓] Checking apt-get for upgraded packages... up to date!
[i] Installer Dependency checks...
[✓] Checking for apt-utils
[✓] Checking for dialog
[✓] Checking for debconf
[✓] Checking for dhcpcd5
[✓] Checking for git
[✓] Checking for iproute2
[✓] Checking for whiptail
[i] Performing reconfiguration, skipping download of local repos
[✓] Resetting repository within /etc/.pihole...
[✓] Resetting repository within /var/www/html/admin...
[i] Main Dependency checks...
[✓] Checking for cron
[✓] Checking for curl
[✓] Checking for dnsutils
[✓] Checking for iputils-ping
[✓] Checking for lsof
[✓] Checking for netcat
[✓] Checking for psmisc
[✓] Checking for sudo
[✓] Checking for unzip
[✓] Checking for wget
[✓] Checking for idn2
[✓] Checking for sqlite3
[✓] Checking for libcap2-bin
[✓] Checking for dns-root-data
[✓] Checking for resolvconf
[✓] Checking for libcap2
[✓] Checking for lighttpd
[✓] Checking for php7.0-common
[✓] Checking for php7.0-cgi
[✓] Checking for php7.0-sqlite3
[✓] Enabling lighttpd service to start on reboot...
[i] FTL Checks...
[✓] Detected ARM-hf architecture (armv7+)
[i] Checking for existing FTL binary...
[✗] Downloading and Installing FTL
Error: Unable to get latest release location from GitHub
[✗] FTL Engine not installed