zulu admin page "url not found" on this server

[pfroelicher]

Hi, 

We installed Zulu 4, when we updated our server, moved it to a macmini in house from AWS. We run 10.15 Catalina, FMS18.03. 

Our setup is special in that we have a reverse proxy, with one external IP we have two internal servers, access.mydomain at 10.x,x.10 and fmserver at 10.x.x.20. 

Everything works on the local machine. I can Web Direct, the Zulu Admin page works, in the 360work Java app I see Zulu4.0 working. xml is enabled. If I publish the stock calendar of the Zulu2SampleData file It publishes.. But.. I cannot login. Checked credentials. If I look at the log files there is not even a login attempt. Somehow the iCal account creation does not hit the server 

Also.. when I try the zulu Admin page from machines within the network I get the "this URL not available on this server" page. 

What's wrong? 

I am an old hand with Zulu, used it since it came out.. Always had ways to make it work.. but this time I tried everything. Something is wrong with this reverse proxy.. This also shows, because Webdirect works on the local machine but from other machines it opens the first file.. but then gets a vaadin JS error and stops working.. I mean.. I see the DB's.. can login.. but as soon as data flow with JS the server somehow does not correctly speak to the client.. This somehow must also give me these symptoms in ZULU. 

I have an open Helpdesk with 360work but have not heard yet.