Possible to sync without a router between Windows, iOS, and Android?

A lot of times I may not have access to a router and a traditional WiFi network.

In these cases, my Android phone is being used as a WiFi Hotspot and the iPad and Windows laptop are both connected to it at the same time.

In this scenario, is it possible to use Syncthing / SyncTrayzor / Mobius Sync to sync all three devices?

An initial problem I’m having is that Syncthing on Android is configured to run only when the Android device is connected to a WiFi network… but the Android phone is the WiFi network when it’s acting as a hotspot, but Syncthing doesn’t run in this case.

I’d say this should work, but a) you obviously need to allow the app to run even without Wi-Fi (probably by enabling the “run on mobile data” and/or “run in airplane mode” conditions), b) Syncthing on Android needs to have global discovery enabled, as local discovery is broken on newer Android versions, and c) any issues specific to Mobius Sync, a commercial/proprietary application, should be handled at their support forums.