The Interstellar Travel mod is not compatible with the Shattered Planet mod.

Interstellar Travel removes space connections to the Shattered Planet. making Shattered Planet unplayable. the mod author has said he is not going to fix it himself. https://mods.factorio.com/mod/interstellar-travel/discussion/698bb85965a7e44ea94f5ba1

the first report about this on that mods page was 6 months ago and nothing was done about it.

either that mod's author has to fix it (unlikely) or a another mod loading after that mod has to add that route back again in the the final-fixes data stage.

Good to know, even though both mods are technically optional here, I've added a note to the main page about the incompatibility, as well as marking it as Not Recommended since it hasn't been updated in 6 months.