Certificate is not a valid PEM certificate

Sounds like Netlify is also hosting your website then - browsers don’t contact GitHub, they contact Netlify, right? There is a competing product called “GitHub Pages” so this isn’t just me playing stupid, it’s a frequent confusion: “I use netlify to BUILD my site, save to GitHub who serves it to browsers” or “GitHub hosts my source code, but Netlify builds it and hosts the website”.

As regards hostname, I was wondering the DNS hostname, rather than the netlify hostname, but I can see that that netlify site has a hostname set.

That hostname is currently hosted entirely at namecheap; you’ll have to turn off the “parking” feature there and follow DNS instructions like these, if you want us to host the site instead:

$ host YOURREALHOSTNAME
YOURREALHOSTNAME is an alias for parkingpage.namecheap.com.
parkingpage.namecheap.com has address 198.54.117.217
parkingpage.namecheap.com has address 198.54.117.210
parkingpage.namecheap.com has address 198.54.117.218
parkingpage.namecheap.com has address 198.54.117.215
parkingpage.namecheap.com has address 198.54.117.212
parkingpage.namecheap.com has address 198.54.117.216
parkingpage.namecheap.com has address 198.54.117.211

Once you decide to turn off parking at Namecheap, let me know if you’d like me to re-examine to try to re-advise!

Sounds like Netlify is also hosting your website then - browsers don’t contact GitHub, they contact Netlify, right?

Yeah, apologies for the poorly worded answers.

That hostname is currently hosted entirely at namecheap; you’ll have to turn off the “parking” feature there and follow DNS instructions like these, if you want us to host the site instead

Okay, I’ll look into that.

you’ll have to turn off the “parking” feature there and follow DNS instructions like these

I’ve done that, what should be the target? I suppose it would be mberkmann.dev?

Nope, you’ll follow this guidance for best performance:

(apologies - I had meant to link that in my last response!)