redirect / proxy_pass with nginx

hi forum,

i'm pretty new to nginx and trying to realize some redirects / proxy passes with it.
the goal is to redirect to different jettys running on different ports on the same server based on the URI. also i need to differ between certificates based on the domain which is used.

the first redirect (/rewrite/here/) and the differentiation between the differend domains works well. but i'm running into trouble for the second pass (/some/location).

the jetty behind the first rewrite is accessible on https://localhost:9443/rewrite/here/ . but the second one is listening directly on https://localhost:8443. so i need to pass https://domain/some/location to https://localhost:8443. it works basically but i end up in a loop while trying to login into the service on the second jetty.

i already tried different settings for the second redirect section but never got it working properly.

thanks in advance!

(nginx.conf attached)