Good tip Jeff, I've used a reverse proxy a few times on commerce websites moving from go-doody and purplehost. Internally all our servers use separate DB servers that are replicated in clusters which keeps the DB in sync no matter what frontend web servers we use. I also found that switching DNS to Amazon rout53 a few days before the transfer helps with propagation time if the client doesn't want to pay for the reverse proxy server setup.

Hi Jeff, is there also a solution for when the old server has to keep serving the pages, but is not allowed to be addressable but it's own url? Situation is like this: my main server is on IIS and is not able to install Wordpress. I have now Wordpress on a different (apache) server under it's own url. Now the main server can serve pages from the apache server under it's own url's (site.com/blog) now, but the old url is also still available. Now I've made it non-indexable in robots.txt, but that's not the very best solution I guess. I've searched for a solution all over the web, but can't find anything. You'd be a real hero if you know something that helps me out.

With tailscale it is easy. It's not the WWW it just what you have Tailscale installed on. You can use your own domain name too. I have CloudFlare and set it up there and put the Tailscale 100 IP in there for A record and my domain name.

Then on Ubuntu server can type just 3 commands to get https with your own domain name.

apt install certbot certbot --manual --preferred-challenges dns certonly -d (your domain name) certbot --apache

It will ask you things and with a long number to copy in to a txt record on your domain name provider. Then you will get https.

Hope they some how add this to tailscale to ask you things if you want to use your own domain name with https.