Redbird reverse proxy issue with meteor hostname+paths

I use Red bird reverse proxy for my meteor apps and my request are redirecly correctly when i use the below configuration i.e subdomain config

var proxy = require(‘redbird’)({port: 80});

proxy.register(“app1.example.com”, “http://127.0.0.1:3000”);
proxy.register(“app2.example.com”, “http://127.0.0.1:4000”);

but when i use domain/ip + paths like in the below configuration

var proxy = require(‘redbird’)({port: 80});

proxy.register(“http://127.0.0.1/a”, “http://127.0.0.1:3000”);
proxy.register(“http://127.0.0.1/b”, “http://127.0.0.1:4000”);

i get the error “no valid route found for given source”. Below is error screenshot
Screenshot from browser

This seems to be a problem only with meteor applications. Plain html pages do work fine with this proxy