Reverse Proxy wss error

Hi

I run two servers behind and AEBS base station.

Server1 runs 10.12.6 and Server 5.3.1 and does a REVERSE PROXY with webapps, like described by precursor.ca tutorial .

This allows me to have only one external IP address where server1.mydomain and server2.mydomain get the distributed internally.

This works ok.. but on server2 I run Filemaker Webdirect, that uses web sockets. So I get in the browser a wss:// error.

I the web app I wrote;

# from http://httpd.apache.org/docs/2.2/mod/mod_proxy.html#proxypass

RewriteEngine On

RewriteCond %{HTTPS} =off

RewriteRule . - [E=protocol:http,E=port:80]

RewriteCond %{HTTPS} =on

RewriteRule . - [E=protocol:https,E=port:443]

SSLProxyEngine on

SSLProxyVerify none

SSLProxyCheckPeerCN off

SSLProxyCheckPeerName off

SSLProxyCheckPeerExpire off

ProxyPreserveHost On

ProxyPassReverse / http://1.2.3.4:443/

ProxyPass / http://1.2.3.4:443/

ServerName filemaker.precursor.ca

Obviously putting in my own IP address of server2 and its name..

However the web socket wss://server2.mydomain does not work.. and web direct fails.

I can login, but as soon as I open a wss connection it does not work anymore. .It is a apache mod_proxy error..

in the apache error log I read

[Sun Apr 19 21:58:04.846046 2020] [proxy_http:error] [pid 598] (70008)Partial results are valid but processing is incomplete: [client 189.62.112.162:49213] AH01110: error reading response

in the browser I read

WebSocket connection to 'wss://fmserver.embatek.com.br/fmi/webd/PUSH?v-uiId=1&v-pushId=341172cf-5d45-454d-972e-3029de5807fa&X-Atmosphere-tracking-id=0&X-Atmosphere-Framework=2.3.2.vaadin1-javascript&X-Atmosphere-Transport=websocket&X-Atmosphere-TrackMessageSize=true&Content-Type=application/json;%20charset=UTF-8&X-atmo-protocol=true' failed: Unexpected response code: 500

Any hints on where to fiddle.

Yours

Pierre