Ошибка установки сервера NTP в Ubuntu 20.04.3 LTS

Я впервые задаю вопрос. Я установил Ubuntu 20.04.3 LTS на сервере, чтобы быть моим NTP-сервером в моей сети. Я пытаюсь установить NTP-сервер, но получаю сообщение об ошибке:

$ sudo apt-get install ntp
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
 ntp : Depends: libopts25 (>= 1:5.18.16) but it is not installable
       Recommends: sntp but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Я также пытался установить sntp, на всякий случай, но та же проблема:

$ sudo apt-get install sntp
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
 sntp : Depends: libopts25 (>= 1:5.18.16) but it is not installable
E: Unable to correct problems, you have held broken packages.

Я также попробовал команду ниже, чтобы установить libopts25 с NTP, но однажды та же проблема снова.

$ sudo apt-get install ntp libopts25
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package libopts25 is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'libopts25' has no installation candidate

Похоже, пакет libopts25 отсутствует или устарел (?). Если этот пакет зависит от NTP, существует ли другая процедура для установки NTP на сервере Ubuntu?

Сервер имеет полный доступ к Интернету. Любые рекомендации будут полезны.