How can you diagnose and fix connection problems affecting only some websites?

When only some websites are inaccessible, first identify which websites, devices, and connection types are affected, then compare browsers, DNS settings, and network equipment in that order. The supplied material includes cases resolved by changing DNS settings, as well as cases where DNS changes did not help and service was restored only after the internet provider intervened. Being able to open other websites does not, by itself, establish that the computer is faulty or that the website has blocked the connection.

First, distinguish between an inaccessible website and a specific page that does not work

Use the same target page when testing to avoid conflating different problems. In one discussion, someone attributed an inaccessible Taobao product page to a login requirement, while other respondents pointed out that the issue was a complete failure to connect, not a login problem. These should not be treated as the same fault.

• List the websites that open normally, those where only the homepage opens, and those that are completely inaccessible.
• Compare whether computers and phones experience the same problem on the home network.
• Then compare the results over a phone’s mobile data connection, and record when the problem starts and when access returns.

In a 2022 case involving the post office website, neither wired nor wireless devices at home could open the site, but a phone could access it over 4G. This kind of comparison describes the scope of the problem more clearly than simply saying “the internet is broken,” but it still does not establish the cause.

Browser and DNS tests may help, but they are not guaranteed fixes

Suggestions in public discussions included clearing cookies and the browser cache, trying another browser, and checking whether antivirus software was blocking access. These are troubleshooting avenues, not confirmation that security software caused the problem. For different connection methods used on the same internet line, another respondent suggested comparing whether they used the same DNS settings.

DNS test results also varied: one poster restored access by switching from automatically assigned DNS settings to two Chunghwa Telecom DNS addresses. In the post office case, however, clearing the DNS cache did not help, and trying several DNS settings on a phone’s Wi-Fi connection still failed to restore access. Thus, changing DNS settings is a testing option, not a universal solution.

Switching to Firefox also failed in that post office case, and at one point ping succeeded even though the browser could not open the website. At least in this case, a successful ping did not mean the web pages were usable.

If equipment tests do not help, give the results to your provider for further troubleshooting

The supplied material recommends first restarting the modem and router. If the problem persists, try connecting another computer with an Ethernet cable. For connections using PPPoE, another respondent suggested testing with a computer connected directly to the modem and, if access still failed, asking the provider to send a technician rather than continuing to change only the computer’s settings.

In the 2022 post office case, a technician eventually tested the connection with a laptop and still could not access the site. Access was restored only after both the modem and the IP address were changed. The original poster speculated that Chunghwa Telecom had blocked the old IP address, but the material provides no confirmation of a block. Because the equipment and IP address changed at the same time, the result does not establish a single cause. When contacting customer support, compile the affected URLs, devices, and connection types, along with the results of browser, DNS, and equipment changes, so further testing can build on what is already known.