about Console proxy url domain

[Sam]

Hello

My  console proxy suffix domain is configured as xyz.somedomain.com and 
use nginx to access the cloudstack console, and it works fine.But after 
I reboot the host servers and cloudstack,I cant access the console 
anymore and shows:502 Bad Gateway.

I think nginx is ok because the other web sites works fine,what's wrong 
with my cloudstack?can someone  help me please,thank you very much.