If you mean you're having trouble getting NPM to work with Jellyfin, here's how I got it working:

Make sure you have “Websockets Support” checked.

Then create a custom location "/", with the following in the advanced config:

## The default `client_max_body_size` is 1M, this might not be enough for some posters, etc.
client_max_body_size 20M;

# Security / XSS Mitigation Headers
# NOTE: X-Frame-Options may cause issues with the webOS app
add_header X-Frame-Options "SAMEORIGIN";
add_header X-XSS-Protection "0"; # Do NOT enable. This is obsolete/dangerous
add_header X-Content-Type-Options "nosniff";

# COOP/COEP. Disable if you use external plugins/images/assets
add_header Cross-Origin-Opener-Policy "same-origin" always;
add_header Cross-Origin-Embedder-Policy "require-corp" always;
add_header Cross-Origin-Resource-Policy "same-origin" always;

# Permissions policy. May cause issues on some clients
add_header Permissions-Policy "accelerometer=(), ambient-light-sensor=(), battery=(), bluetooth=(), camera=(), clipboard-read=(), display-capture=(), document-domain=(), encrypted-media=(), gamepad=(), geolocation=(), gyroscope=(), hid=(), idle-detection=(), interest-cohort=(), keyboard-map=(), local-fonts=(), magnetometer=(), microphone=(), payment=(), publickey-credentials-get=(), serial=(), sync-xhr=(), usb=(), xr-spatial-tracking=()" always;

# Tell browsers to use per-origin process isolation
add_header Origin-Agent-Cluster "?1" always;

# Disable buffering when the nginx proxy gets very resource heavy upon streaming
proxy_buffering off;