CentOS

You seem to have missed the Red Hat announcement that they were killing CentOS Linux 8 about 3 years ago. You need to pick a newer rebuild - I'd recommend either Rocky or Alma as Stream is too beta-y to be trusted.

Elevate sounds good but before use, a backup of the original is essential.

Check you don't have duplicate files pertaining to the same adapter in /etc/sysconfig/network-scripts

The "issues" you will face are that CentOS 7 dies in two months so there will be no more updates for it, security or otherwise. It's a dead distro that should not be used any more and certainly not after 2 months time. Putting a lot of work into updating openssh on it is pointless as the entirety of...

No. And it's not worth the effort of trying either since CentOS 7 goes EOL in less than 2 months time. Pick a new distro and start your migration to it.

CentOS is dead, you need to move to something else.

Check in /proc/cmdline to see if your changes took effect.

CentOS is dead. Use one of the other RHEL rebuilds instead.

https://access.redhat.com/security/cve/CVE-2023-6931 RHEL 7 is listed as "Out of support scope" which means it's too old and the vulnerability not important enough. It also says It is not possible to trigger this issue with the default kernel.perf_event_paranoid sysctl value 2. You may check it with...

Is this a real system or a container?

bash-4.4# ls -laZ /var/lib/tftpboot total 2 drwxr-xr-x. 2 root root system_u:object_r:container_file_t:s0:c128,c144 1024 Jan 4 16:00 . drwxr-xr-x. 15 root root system_u:object_r:container_file_t:s0:c128,c144 1024 Apr 27 15:41 .. -rwxrwxrwx. 1 root root system_u:object_r:container_file_t:s0:c128,c14...