Tested with VCD 10.5.1
In proxy host > advanced > add the below.
fastcgi_buffers 16 200k;
fastcgi_buffer_size 100k;
proxy_buffer_size 128k;
proxy_buffers 4 256k;
proxy_busy_buffers_size 256k;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection “upgrade”;