....(snip) upstream HTTP_WWW { server 198.51.100.11; server 198.51.100.12; } upstream HTTP_ACME { server 192.0.2.101; } server { listen 203.0.113.11; server_name www.example.com; location ^~ /.well-known/acme-challenge/ { proxy_pass http://HTTP_ACME; } location / { proxy_pass http://HTTP_WWW; } } ....(snip)