You could always try altering your DNS server. I changed mine to google's public server, the setting is 220.127.116.11 primary and 18.104.22.168. secondary.
You can google how to change it for your operating system. takes a couple of minutes to do it.
There are pros and cons to doing that, if you are concerned about privacy it means google can track every site you use. Additionally it means all your DNS traffic has to negotiate its way through many servers and back instead of talking directly to your ISP's DNS server.
In reality its rare to have a DNS problem these days, normally your computer points to your router's DNS server, the router's DNS server talks to your ISP's DNS server. DNS is cached at the ISP, cached at your router and cached at your computer.
DNS propagation has been changed enormously in the last couple of years whilst it used to take up to two days for DNS to propagate round the world it usually happens within the hour these days and sometimes in seconds round USA and Europe. The occasional problem is the caching on your router and your computer doesn't keep up with the changes that fast never mind which DNS server its pointing at, but most sites have fixed IP addresses so the DNS rarely needs to update.
Sorry if that's a bit techie but just to help people follow, DNS is the table of website names to their IP addresses. Whilst you type in a name (url), the traffic to and from your computer uses the IP address which is basically an identity number. You need a DNS system because your normal computer's traffic (http) couldn't pick up a DNS table because it wouldn't know the IP address or route to fetch it from. There are other matters as well but that doesn't matter to understand the basic functionality.