I read this book maybe 10 years ago. I read it in German; I don't think it was a native German book though, but rather a translation.
There was a protagonist whom we followed across this book. The main thing was that there were teleporter disks, which would bring you to other places/worlds. But, you could not consciously choose where to go, instead the disks would decide where you would go, that is "what you truly and subconsciously need most right now" if I remember correctly. Which leads the protagonist to a long pilgrimage across a lot of worlds.
One of them was a planet where the inhabitants fought an eternal war; the two civilisations were divided by the equator (or did the border move throughout the battles?), and both halves were fighting each other since many many years. I think the inhabitants' technology level was not too high, I think it was more like a bit tribal, and they were like murlocs (those amphibian tadpole-like things from the Blizzard/Warcraft universe, and not Morlocks, from The Time Machine) or something. No one could remember the reason for the war and they did not care, or it was entirely insignificant.
Also, the worlds had different technology levels. For example, he/she finds several aircraft/spaceships, some more advanced, some less. Many had like a dark black fog/nothingness in it instead of a seat with belts, which would fixate you, but one ship had this darkness only as a seat, the other as the whole cockpit/ship.
There was another planet, where war was also going on, and he joined the fight and rode an aircraft-bike thing.
There might have been a chapter on some kind of a military base which he/she explored. Could be that I mix that up with another book.
I don't remember the gender of the protagonist, or time, or if starting place was Earth.
I initially thought it could have been a Lukianenko, because I read a lot of them at that time, but I could not find a matching book there.