Post Images Broken on External Server

My issue is with post images that are uploaded by the internal users.

My WordPress site has one installation but is accessed through two URLs for internal network users and external web viewers.

Our IT Dept set it up this way for security purposes. WP-Admin is only accessible behind a firewall on the internal network.

Internal network users access the site through https://internal.machine.name/blog for administration and to post articles. https://www.ourwebsite.com/blog is for external viewing.

Here is the crux of the issue: images that are uploaded internally use the direct path of https://internal.machine.name/blog/… That internal URL is then also used when viewing the blog outside the network. Only that URL doesn’t work because those images aren’t available due to the firewall.

Is there a way so that images are referenced by relative path only?

Or is there a common setting to make this work that I’m missing?

Thank you in advance for your assistance. I’ve been banging my head against this for some time and haven’t found a resolution.

Edit: I had this working with the “Relative Image URLs” plugin but I now see that it’s only compatible to 4.0.5. Externally viewed post images must have stopped working with my last update of WordPress. I would have not noticed the break since I view the blog internally.