ios failing ota

So far I can no longer update iPhone on its’ own. It’s incremental updates just don’t install (phone loads it, verifies , restarts and nothing, same old version).

After a couple failed updates it starts to try install full update instead of incremental - for example, current iOS 15.3 is 5.17gb. This one also fails so far. The only way I can update is through iTunes. Issue started with iOS 15. Pre 15 I could update it without Mac