can't get websocket connection working on Apple Watch

I have an app that uses a websocket connection to the Mac on the local network — it works fine on the iphone — it works fine on Apple Watch simulator on a real Apple Watch I get the message

nw_endpoint_flow_failed_with_error [C9403 192.168.0.35:10010 failed parent-flow (unsatisfied (Path was denied by NECP policy), interface: ipsec1, ipv4, ipv6, proxy)] already failing, returning

I can't find any information on that NECP policy and no cure for this error. Please help me

it's Xcode 26.2 and watchOS 26.3 if it matters