I have a local Magento 2 site, not much changed recently. But all of a sudden, all custom routing, no matter what module it is from, is broken. In admin and frontend, I get 404s (from Magento, not a default php 404) for all routes that are not Magento core.
I downloaded everything from the working live site, just in case I'm missing anything, rolled back the code several months just to see if it fixes it, synced the database, reinstalled composer, compiled and upgrade and cleared cache a million times.
I disabled all third party modules except one that has custom routes, then swapped it for another one. Same result. All 404s.
I'm at a total loss - how can I debug this?