This is interesting, as RT reflections don’t support occlusion/GI in the same way lumen can. That fragmentation looks like a shadowing issue more than a GI issue, so I’d ask what your shadowing solution/CVars are first.
Lumen viewdistance can be maxed to 800 meters in the PPV, but beyond that, you’ll have to set up ‘far field’, an HLOD system that lets lumen do long-distance traces. It’s a bit of a hassle at first, but way cheaper than standalone RT when it comes to supporting larger view distances at detial.