Cannot access certain sites with Router Archer A7
I successfully installed the router and it was allowing me to access my business websites. One day it stopped and I began receiving notices that the web page could not be opened because the browser couldn't establish a secure connection to the server where my sites reside. I have tried various devices and various browsers and receive the same error notice. I called my web host and there was not problem on their end - they could view the sites. They suggested I contact my ISP. I called the ISP and they informed me they are not blocking the sites. I contacted TP-Link's support team and was asked to see if I can connect to the sites with my device hardwired to the ISP modem. I can connect then. I can also connect on my iPhone on cellular. There is clearly something in the router's configurations that are blocking these sites. I have looked at the settings for the primary DNS and changing it to 8.8.8.8. It's already set to that. I am at my wit's end and will be returning this router if someone is unable to provide a solution. I don't see that there is any way to whitelist certain domain ip addresses. Please help.