I described here
https://www.mediawiki.org/wiki/Extension:Math/Restbase
how I set up restbase at my own server.
@TitusiMW does that work for you as well?

Thanks @Physikerwelt

For the restbase server config.yaml, I concatentaed your instructions under the config.example.yaml that comes in the package. Is this what you meant? If I dont do that just use your instructions as the config.yaml then I get a bunch of Null Object errors.

I am able to install and start both Mathoid and RestBase servers using your instructions. [I had to change relative paths for some files in the config.yaml files for both of them ... but generally they worked ok.]

But Math rendering is still not working.

Question1:
If I use your config files as it is then, what should be the value of $wgMathFullRestbaseURL ?
Can this variable use http://localhost since I am only accessing it from inside the host only?

Question2:
In the instructions for testing the RestBase installation, what is the equivalent to this suggestion: http://localhost:8081/wikimedia.org/v1/?doc
for my private installation (lets say my wiki is at: https://wiki.abc.com/wiki/page1)?

@TitusiMW:
Q1: You can not user localhost, since the client browser needs to fetch the fallback images from that source, for example:
$wgMathFullRestbaseURL = "https://wiki.abc.com:8081/wikimedia.org/";
Q2: I don't understand the question.