Why is my IONOS 1&1 root not redirecting correctly over ssl?

Question

I have a 1&1 IONOS domain for my heroku app. the www subdomain works fine, with a CNAME setup for it. but I'm trying to redirect the root url to the www subdomain. this also works fine for http, but if the url is typed in as https://example.com, I get a ERR_SSL_PROTOCOL_ERROR (on chrome, other browsers have different errors). this is on any device, regardless of clearing cache and history etc. my heroku logs show it's never reached, so it must be an issue within 1&1. theres an ssl cert set on the domain with 1and1, as well as heroku's ACM. any ideas?

Answer 1

To make the four URL variations (http://example.com, http://www.example.com, https://example.com, and https://www.example.com) point to a different SSL hosted site (heroku, cloudfront, etc), you need three things in IONOS:

1. Under DNS settings, add a CNAME entry for the www subdomain that points to your SSL hosted site (example.herokuapp.com)
2. Set up an HTTP Redirect under Domain Forwarding to https://www.example.com (don't check the box that states "Also set up for www subdomain")
3. Make sure you have an SSL wildcard certificate for *.example.com installed and attached to your domain in IONOS

It looks like all you are missing is number 3. After that, the redirect that you have setup should work as expected.

Note: example.com should be replaced by your actual domain in all of the above.