Product images blocked by robots.txt +Image hosting best practice

[ADGENCYDEV]

Dear all, 

Site http://ht26.com/ is running on PS 1.6.1.1

All images from media library are hosted via subdomains

• https://media1.ht26.com/
• https://media2.ht26.com/
• https://media3.ht26.com/

The problem: none of the image get indexed while you run via GOOGLE IMAGE SEARCH the operator code

• site:media1.ht26.com
• site:media2.ht26.com/
• site:media3.ht26.com/

 

When I try via search console manually indexing an image sample , google claims the URL can't be indexed cause robots.txt file is blocking the image url (https://snipboard.io/c6zg1b.jpg )

https://media3.ht26.com/robots.txt seems to be the default robots.txt content (see at bottom SITEMAP XML Referenced is the Root' one)

I'd be grateful if I can get your advice on 3rd questions:

1) What are the best practice for image hosting? I see many PS site with image hosted under the root domain (I mean at subfolder), is there any PROs to have image sitting at subfolder rather than Subdomains?

2) Although I've screened each single Disallow rule @ https://media1.ht26.com/robots.txt not finding WHAT could disallow google bot access to url path "/10368-small_default/lait-claircissant.jpg" - anyone might have a hint?

3) To force indexing on GOOGLE IMAGE SEARCH of all product images. Beside opening fully the robots.txt of the 3 Media* Subdomains by keeping as sole content 1 rule: "disallow: " is there any other action you could think about?

Many thanks in advance fo your precious help

Alex

Edited January 30, 2020 by ADGENCYDEV (see edit history)