You have two frontends listening on port 80, that’s wrong and will certainly cause issues, you can only listen on a port once.
Please share:
- the complete and actual configuration (the configuration above is missing at the very least the
formation.univ_bfc.frbackend configuration) - which of the subdomain has the problem
- post the haproxy log message of the request failing (refer to proper logging configuration if you don’t see anything)