HA Proxy Reverse Proxy Help [solved]

[docb]

EDIT: Now it works with this configuration. After some reboots and leaving everything as it is for 1 day it works.  Sometimes they have their own life ;-)

Hi,
I have followed several guides to set up a reverse proxy with ha proxy but I am not sucessfull (e.g. https://docs.opnsense.org/manual/how-tos/haproxy.html, https://www.frankysweb.de/exchange-2016-opnsense-haproxy-und-lets-encrypt/). Unfortunately they do not refer to ha proxy 2.6 but I think I've managed to "translate" some of the descriptions (i.a. ACL -> Rules).
If I use NAT, I can reach my webserver from the internet, but not with HA Proxy. Could someone please look over my config and tell me where my error is?
Firewall -> Rules -> WAN -> ICPv4TCP * * * 80 (HTTP) *      [should allow any http traffic to any destination]
Services -> HAProxy -> Configuration:

• 1. Real Server
• Name: us80
• FQDN or IP: 192.168.2.4 (this is where my apache is reachable
• Port: 80
• SSL: unchecked
• Verify SSL: unchecked
• 2. Virtual Services -> Backend Pool
• Name: us80_backend
• Mode: HTTP (Layer7) default
• Balancing Algorythm: Source-IP Hash default
• Server: us80
• nothing else changed
• 3. Rules & Checks -> Conditions
• Name: us80_acl
• Condition type: Path starts with
• Negate condition: unchecked
• Path Prefix: /*
• 4. Rules & Checks -> Rules
• Name: us80_rule
• Test type: IF default
• Logical operator: AND default
• Execute function: use specified Backend Pool
• Use backend pool: us80_backend
• 5. Virtual Services -> Public Services
• Name: us80_public
• Listen Addresses: 127.0.0.1:80, 192.0.0.2:80 (WAN Address, I've tried it with only this address too, also 0.0.0.0:80 did not work)
• Type: HTTP / HTTPS (SSL offloading) default
• Default Backend Pool: us80_backend
• Select rules: us80_rule (does not work without rule either
• nothing else changed

I am thankful for any hints!