ANSWER: Occasionally after we’ve completed a new website migration to our VPS servers, a client will contact us saying they are still “seeing” their old site, or that loading speed hasn’t improved, or that certain errors appear (i.e. 404 error, etc). In nearly every case, this is due to slow DNS propagation. DNS is not a perfect technology — in fact far from it — and is infamous for being the “weak link” in the way the internet works.
Modern DNS technology i.e. Anycast DNS has nearly eliminated the years of issues associated with DNS, partically slow propagation of DNS changes around the world. But still there are instances of issues sometimes where a client based in perhaps a small city or whose ISP provider is a bit outdated might see slow DNS updates.
In this case we recommend installing and connecting to the web via a VPN application so that you can surf the web from various cities around the world over an encrypted tunnel, meaning that you can bypass the local DNS issues and/or data packet loss that your ISP is suffering from.
To check your DNS propagation around the world there are some free tools available: