Try to Reload the webpage while bypassing the cache using one of the following steps:

• Hold down the Shift key and click the Reload button in the navigation toolbar.

OR

• Press Ctrl + F5 or Ctrl + Shift + R (Windows and Linux)

Let us know if this solves the issues you are having.

You can try the DNS Lookup tool on the about:networking page. You can open "about:" pages via the location/address bar

• "about:" is a protocol to access special pages

Did you try to restart (power off/on) the router?

Boot the computer in Windows Safe mode with network support to see if that has effect in case security software is causing problems.

• https://www.bleepingcomputer.com/tutorials/how-to-start-windows-in-safe-mode/
• https://www.7tutorials.com/4-ways-boot-safe-mode-windows-10

You can check the connection settings.

• Options/Preferences -> General -> Network: Connection -> Settings

If you do not need to use a proxy to connect to internet then try to select "No Proxy" if "Use the system proxy settings" or one of the others do not work properly.

See "Firefox connection settings":

• https://support.mozilla.org/en-US/kb/firefox-cant-load-websites-other-browsers-can

thank you my friends. after some try and search, I found that the problem was because of limitations to my country.

Hopefully, I see the day when everyone is satisfied with their rights and does not resort to bullying, war and killing, sanctions in order to violate the rights of other nations.

   The members of a body are one
   Which are the essence of creation
   What a painful time
   Don't leave the other members
   You don't care about the hardships of others
   Let them be called human beings

   banī ādam a'zā-ye yek peykar-and
   ke dar āfarīn-aš ze yek gowhar-and
   'o 'ozvī be dard āvarad rūzgār
   degar 'ozvhā-rā na-mānad qarār
   to k-az mehnat-ē dīgarān bīqam-ī
   na-šāyad ke nām-at nahand ādamī

The literal translation of the above is as follows:

   "Human beings are members of a whole,
   since in their creation they are of one essence.
   When the conditions of the time brings a member (limb) to pain,
   the other members (limbs) will suffer from discomfort.
   You, who are indifferent to the misery of others,
   it is not fitting that they should call you a human being. "

"Mr. Saadi Shirazi"