It often happens that some sites do not open on your computer, although until recently, everything was fine with them. Such a problem can greatly spoil the mood of almost any user, not to mention newcomers, so you should immediately understand the reason for its appearance.
So why the browser does not open some sites. Perhaps you should start the search for the guilty person from the browser itself. First of all, answer the question: “Do you know that browsers have version numbers and the browser requires updates from time to time”? If the answer is yes, then the following information will probably not be useful to you, but if you belong to naive users, then reading the following information will definitely not hurt you.
It is worth considering that most of the website typesetters, which are simply tired of the abundance of all kinds of browsers on the market, simply stopped supporting older versions. In this regard, it is worth mentioning the tragedy of Microsoft Corporation, which only in the last couple of years has achieved success in the matter of "funeral" of the old IE6, which has already become a long-standing nightmare of many website creators. So if your browser does not open some sites, and you see an inscription like “The site does not support your browser” on the screen, it makes sense to go to the site of the creator of the software you use and update it to the latest version.

However, in this regard, it is worth giving advice that it is not necessary to follow the links on all sorts of pop-up windows that offer you an update. The fact is that deeply dear writers of viruses and trojans have long and successfully used the total computer illiteracy of users, transferring them to their sites in order to download a whole host of malware. But some sites do not open not because of this ...
Do not forget that the site must be “stored” somewhere, located on physical servers. And from time to time they like to “fall”, which happens even with powerful corporations like Google, whose equipment also sometimes crashes. If your favorite site does not open, and something similar to “Server Error ...” appears on the monitor, then it won’t hurt to just wait until technical support and the administration of the resource fix the problem.
And some sites do not open yet because some excessively lazy layout designer did not consider it necessary to “sharpen" his creation for a specific browser type. True, they open in this case, but what appears on the monitor is more like a mishmash of heaps of pictures and letters ...
By the way, it will not be superfluous to check the settings of your antivirus program and firewall. In this regard, it is worth mentioning the fact that the same Dr.Web Security Space, with the "Parental Control" and "Block unwanted sites" options enabled, prohibits access to many popular resources. So, rummage around in the settings of security programs, although think before that about whether you really need to get to the site that has received the category of “Spreading the virus”?
In a word, there are plenty of reasons for the fact that some sites do not open, and you should not blame your Internet service provider right away, although it is often possible for someone to block a resource.