I have a Netatmo Ring bell for which the binding has yet to be updated. So I ended up using their REST API to retrieve some information from it. That allowed me to retrieve an image url about recent snapshots taken by the camera.
I integrated that into my sitemap by updating the Image item with the proper url. This all works fine as long as I access the Basic UI from my local network.
I am also using myopenhab to acces my sitemap remotely. For that I mainly use the android app, but my issue also happens from a windows PC using the browser to access the sitemap.
This is not a general problem but seems to be specific to the image url retrieved from the netatmo smart video ring bell.
To reproduce this you could make a very simple sitemap only containing an Image specifying the above link as url parameter. It works locally, but not through myopenhab.
I am still on OH 2.5, but I also tried a blank 3.1 installation to see if this would incentivise me to migrate to 3.x but I had the same issue.
There should not be any kind of authentication for this link. Anyone should be able to access it.
I read stuff about that something like this can be caused when you use Paper UI or such, but this is all file based.
I have no clue what is going on. Hope someone here does