Error: curl: (6) Could not resolve host: install.pi-hole.net

I have Pihoile instalated in contejner router Turris Omnia. It's in operation for several weeks. Previously the update instruction worked normally, now I receive an error.

apt-get update ...  response ready
apt-get upgrade ...  response ready 
apt-get install curl ...  response ready

curl -sSL https://install.pi-hole.net | bash
curl: (6) Could not resolve host: install.pi-hole.net

curl -sSL https://104.236.99.8 | bash 
(Just test-according to the assumption certificate error)

Are you saying you installed Pi-hole on a router?

Run pihole -d for a debug token.

Thanks for interest. Command pihole failed in the past, always error. Pihole command failed to run - message "not found". The command Pihole i uninstalled, always after a short time stopped working the rules blacklist. Many afflictions, no indication of errors.

Layman I believe that problems can cause direct default DNS to CZ. NIC Resolver on Router Omnia.

Maybe in the future, Pi-hole still try.

How do you have it containerized on the Omnia? Are you running Docker or do you have it jailed with another system?

Yes, it was installed in a container on the router Turris Omnia. I am not a great expert, questions for me must be very simple and accurate. STep by step.
......
I think Debian -Jessie container

lxc-create -P /mnt/sda1 -t download -n Pihole
lxc-attach -P /mnt/sda1 -n Pihole
apt-get update
apt-get upgrade (potvrdit Y)
apt-get install curl (potvrdit Y)
curl -sSL https://install.pi-hole.net | bash

https://doc.turris.cz/doc/cs/public/pihole
https://forum.turris.cz/t/zprovozneni-pi-hole-omnia/6219
https://doc.turris.cz/doc/cs/public/pihole?s[]=pihole

We don't directly support running inside lxc containers. If you were missing the pihole command then you didn't have the software installed correctly or you were issuing the pihole commands outside of the lxc container.