Ubuntu: 'Not Found' error on restore

I’m trying to restore the test of my backup that I made and it fails with “Not Found” right when I enter ‘Restore’ (without even trying to do actual restore)
When I check where is the problem while examining requests that are being sent by UI I see 404 error for this get request:

Similar request that was sent right before this one works fine:
So I assume there is an issue with ‘/’ being added there?

I’m accessing duplicati UI from remote address by apache proxy to

So, I figured that I can access duplicati without apache proxy trick and it works fine without it if I just enable remote access and load through http://[mydomain]:8200/
Must be an issue with apache