After another extra-painful attempt to upload some pictures and update an older post I left my hosting company and went back to running this site on WordPress.com. I just was too fed up with the situation. Seemingly uploading 6 images is too much too ask when 5 is totally enough.
It wasn’t even a real rage-quit, I’m good at those. I was in contact with support and tried to solve the issue. Even though the replies were very thorough, they were also not really helpful in the grand scheme of things. It all would have resulted in putting-in even more time and effort to fix, or to find the actual reason for the failures. More time and effort that I’m willing to put into or up with.
So, I did the one thing that I’m already good at and exported/imported posts back into my old instance on Worpdress.com and after 20min I was done. Everything is fast and snappy again, and guess what, uploading stuff naturally works as expected.
Of course, I will loose (again) some of the benefits of hosting the blog myself, such as custom plugins and themes and some embeds, but at least things will work. If I really miss some of the plugins, I still have the option to upgrade my WordPress.com plan, which as of recently allows for installing stuff. The latter would give me the best of both worlds, but seems overkill for now.
Once the DNS has properly propangated, which might still take a while, the site should be running smooth and fast again.