It’s a bit tangential, and not anything like what I’d propose as to how the setting works, but “Oh, hey, the interstellar travel network is collapsing” is the core story in John Scalzi’s most recent trilogy of books, The Interdependency.
As part of the premise, there are nearly no human-habitable planets, meaning most of the human settlement of the galaxy is in artificial habitats, none of which are likely to survive if all interstellar trade collapses. Only a few of the implications might be applicable, but, regardless, it’s a very enjoyable series. Recommended.
Buck Rogers in the 25th Century was crap SF, and so very much of its era, and, God help me, I watched way too much of it because it was “Christians in Rome” time for SF fans and TV.
The one thing I always liked about the show (really, the one thing) were the stargates. And, as God is my witness, there are no good videos of the effect. Only one episode is even partially repped in online video, and even there I can only find a partial rendition of the BRit25C stargate effect … which was this:
(The one above I made myself.)
The original sequence, as I recall, starts with blackness, and then four points that spin-starburst into light, then the GIF, then spin-starburst to darkness.
And that’s what I always think of as a stargate, even though that is not what I think of in the context of our campaign.
And while we’re accustomed to such things being a single ring, there’s no reason why it can’t go all Time Tunnel on us … perhaps less of a gateway than a hyperlinear accelerator …
(Reading how tidal-locked worlds are something really cool that is inspiring fresh science fiction about this strange new concept. Glancing up at shelves of Golden/Silver Age SF stories set on Mercury back when we thought it was tidal-locked …)
( (Okay, to be fair, most of the new SF is about Earth-ish planets, not Mercury hell-holes.) )
“They say that jellyfish helps the memory. Maybe yes. Maybe no. But none of us ever imagined the Great Plasma Jellyfish would itself hold the memories of the Forerunners, and how to restart the Gates they left for us …”