Which one of these problem is server side?

[KernelOops]

The largest contentful paint, is a "perceived" time from the user's perspective. It gives you an indication about how long it takes for the page to appear usable to the user.

A 6 second delay, means the user keeps looking at his browser for 6+ seconds waiting for the page to draw HTML/CSS/Javascript and image content, while incapable of interacting with the page. Indeed that is a big delay for the user to keep looking at his screen waiting for your page to work...

It usually implies very bad HTML/CSS/Javascript code, like some horrible and bloated wordpress theme. Other times, its just one bad item that causes all that delay...

I don't think internet speed is a problem for most of the Western world, but it is a serious problem for many developing countries.

[hack3rcon]

The largest contentful paint, is a "perceived" time from the user's perspective. It gives you an indication about how long it takes for the page to appear usable to the user.

A 6 second delay, means the user keeps looking at his browser for 6+ seconds waiting for the page to draw HTML/CSS/Javascript and image content, while incapable of interacting with the page. Indeed that is a big delay for the user to keep looking at his screen waiting for your page to work...

It usually implies very bad HTML/CSS/Javascript code, like some horrible and bloated wordpress theme. Other times, its just one bad item that causes all that delay...

I don't think internet speed is a problem for most of the Western world, but it is a serious problem for many developing countries.

No, I mean is the Internet speed of web server. If the web server Internet connection is not high then can it make website slow?

[hack3rcon]

Where is the best place for write that configuration lines?

[pjsr2]

(Largets Contentful Paint 6.414 s)

But why this is red? :

When you load a web page in Firefox, open the Web Developer Network pane (Short-cut: Ctrl-Shift-E ) you can see which elements are loaded, their size and how much time that took.
Look for slow things. Look for unnescesary large files. Something slow might be loaded from a third party server. Perhaps a slow java script function on your page.

[pjsr2]

No, I mean is the Internet speed of web server. If the web server Internet connection is not high then can it make website slow?

The report indicates that total amount of data transferred is 4183 KB (bytes, not bits).
If your web server uplink speed is 10 Mbps (bits), and all data is coming from your server, 4183 KB would take roughly 4 s.

As a comparison: loading the front page of one of the national newspapers in my country requires a data transfer of 750 KB.

[hack3rcon]

(Largets Contentful Paint 6.414 s)

But why this is red? :

When you load a web page in Firefox, open the Web Developer Network pane (Short-cut: Ctrl-Shift-E ) you can see which elements are loaded, their size and how much time that took.
Look for slow things. Look for unnescesary large files. Something slow might be loaded from a third party server. Perhaps a slow java script function on your page.

What is your opinion about it? :

Capture.PNG (70.38 KiB) Viewed 656 times

[KernelOops]

wow those are A LOT of separate CSS scripts... very unoptimized and logical to get so many errors.

try using a wordpress plugin like the W3 total cache.

[hack3rcon]

Thank you for your advice.
Why website performance showing different results?
It is a result from https://gtmetrix.com/:

New-Test.PNG (96.12 KiB) Viewed 630 times

[KernelOops]

You clearly have some efficiency and optimization issues. 118 requests is too many, 4MB of data is also too much and 10 seconds load time is very bad.

Here are two of my sites, one is an ecommerce site (heavy duty stuff) and the other is a simple blog (lightweight and simple).

.
ecommerce:

eshop.png (120.08 KiB) Viewed 592 times

.
.
blog:

blog.png (113.9 KiB) Viewed 592 times

[hack3rcon]

You clearly have some efficiency and optimization issues. 118 requests is too many, 4MB of data is also too much and 10 seconds load time is very bad.

Here are two of my sites, one is an ecommerce site (heavy duty stuff) and the other is a simple blog (lightweight and simple).

.
ecommerce:

eshop.png

.
.
blog:

blog.png

Thank you for your help.
Is it because of Apache configuration or web site programming or Hardware equipment?