Why did enabling Upnp break my haproxy setup?

[opnuser1]

I had haproxy configured to forward ports 80, 443 to multiple servers based on the hostname.  it was working great.  then, I enabled Upnp, and it completely ruined the haproxy setup.  None of the sites were working in that it would just give cert errors and such.  The listen address are 0.0.0.0:80 etc. 

Once disabling Upnp, it all works again as expected.  I'm just curious what is the explanation.  Thank you.