two servers on different machine with one IP

Question

I have Nextcloud server running fine with ip 192.168.0.1 Installed collabora online server on another machine with IP 192.168.0.2 I have one public IP and two separate domains for those servers pointing at the same piblic IP

what I try to do is use nginx to distribute the traffic accordingly. The configuration for the Nextcloud is working fine:

upstream php-handler {
    server unix:/var/run/php/php7.0-fpm.sock;
}

server {
    listen 80;
    listen [::]:80;
    server_name first.domain.com;
    # enforce https
    return 301 https://$server_name$request_uri;
}

server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name first.domain.com;
...

now I am putting second config for collabora server:

server {
    listen 80;
    listen [::]:80;
    server_name second.domain.com;
    # enforce https
    return 301 https://$server_name$request_uri;
}


server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name second.domain.com;
    ssl_certificate /etc/ssl/private/server.crt;
    ssl_certificate_key /etc/ssl/private/server.key;
    ssl_password_file /etc/ssl/private/server.pass;


    location / {
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header Host $host;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_pass https://second.domain.com;
    }
}

I have added 192.168.0.2 second.domain.com to the hosts file

this server also has nginx running:

server {
   listen 443 ssl;
   server_name second.domain.com;

    ssl_certificate /etc/ssl/private/server.crt;
    ssl_certificate_key /etc/ssl/private/server.key;
    ssl_password_file /etc/ssl/private/server.pass;
    # static files
    location ^~ /loleaflet {
        proxy_pass https://localhost:9980;
        proxy_set_header Host $http_host;
    }

    # WOPI discovery URL
    location ^~ /hosting/discovery {
        proxy_pass https://localhost:9980;
        proxy_set_header Host $http_host;
    }

    # main websocket
    location ~ ^/lool/(.*)/ws$ {
        proxy_pass https://localhost:9980;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
        proxy_set_header Host $http_host;
        proxy_read_timeout 36000s;
    }

    # download, presentation and image upload
    location ~ ^/lool {
        proxy_pass https://localhost:9980;
        proxy_set_header Host $http_host;
    }

    # Admin Console websocket
    location ^~ /lool/adminws {
        proxy_pass https://localhost:9980;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "Upgrade";
        proxy_set_header Host $http_host;
        proxy_read_timeout 36000s;
    }
}

the collabora window opens blank in nextcloud when i open a file

nginx on the nextcloud server gives response 400.

"GET /lool/https%3A%2F%2Ffirst.domain.com%2Fapps%2Frichdocuments%2Fwopi%2Ffiles%2F6932_ocqfsn9n2v8v%3Faccess_token%3DOObPuPjPgz7ycgmvNAklYGo1clIANWXU%26access_token_ttl%3D0%26permission%3Dedit/ws?WOPISrc=https%3A%2F%2Ffirst.domain.com%2Fapps%2Frichdocuments%2Fwopi%2Ffiles%2F6932_ocqfsn9n2v8v&compat=/ws HTTP/1.1" 400 0

So somehow I am not doing the redirection right. I need help with the nginx configurations. I know collabora server works because when I set second.domain.com 192.168.0.2 in the hosts file of the client and no redirection from nginx then it works fine