@György-Farkas
Thank you very much.)
Thanks to you, the apache was installed.

Another problem came up.

root@Omega-****:~# apachectl start
(125)Address in use: AH00072: make_sock: could not bind to address 192.168.0.22:80
no listening sockets available, shutting down
AH00015: Unable to open logs

Why can't I install the apache?
The following message appears :

root@Omega-****:/# opkg install apache
Unknown package 'apache'.
Collected errors:

• opkg_install_cmd: Cannot install package apache.