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Federate with https://lemmit.online ?
(waveform.social)
I like Photostructure as a way to browse my photos. It does logical deduping, and automatic organization of your photos (if you want it to). Like some others mentioned in this thread, it's a very young software, but the developer is very active and transparent about the progress.
Edit to add link: photostructure.com
If your router has NAT reflection, then the problem you describe is non existent. I use the same domain/protocol both inside and outside my network.