Getting ERR_ABORTED 502 (Proxy Error) using apache, node.js express and socket.io

Hi there, Im having a problem with proxy on apache, when i run my app and upload several images i get no error but when using bigger files such as .mp4 files (50mb), the first files upload without a problem but then if it’s several files I get: ERR_ABORTED 502 (Proxy Error)

My config file for my domain is:

        ServerAdmin info@domain.net
        DocumentRoot /var/www/domain.net/public_html
        ServerName domain.net
        ServerAlias www.domain.net

        ProxyPreserveHost On
        ProxyPass / http://127.0.0.1:3002/
        Alias /error/ “/var/www/domain.net/public_html/error/”
        ProxyPass /error/ !
        ErrorDocument 503 /error/503.html
        ProxyPassReverse / http://127.0.0.1:3002/

        RewriteEngine On
        RewriteCond %{REQUEST_URI}  ^/socket.io            [NC]
        RewriteCond %{QUERY_STRING} transport=websocket    [NC]
        RewriteRule /(.*)           ws://localhost:3002/$1 [P,L]

        <Directory /var/www/domain.net/public_html/>
                Options FollowSymLinks
                AllowOverride all
                Require all granted
        </Directory>

        # Available loglevels: trace8, ..., trace1, debug, info, notice, warn,
        # error, crit, alert, emerg.
        # It is also possible to configure the loglevel for particular
        # modules, e.g.
        #LogLevel info ssl:warn

        ErrorLog ${APACHE_LOG_DIR}/error.log
        CustomLog ${APACHE_LOG_DIR}/access.log combined
        ErrorDocument 503 /50x.html

        <Files "50x.html">
                <If "-z %{ENV:REDIRECT_STATUS}">
                        RedirectMatch 404 ^/50x.html$
                </If>
        </Files>

Any ideas or help? Thanks.