I contacted the hosting support. They told me to ask what configuration is wrong or should be changed? Or which parameter or addressing is incorrectly located in the config that caused this error?
I have already told you that your provider isn't responsible for this incorrect configuration, because in 10 out of 10 cases the cause is only a few centimeters or inches in front of the monitor. That means you installed some questionable plugin that was doing this crap. Therefore I can only advise to check your plugins and to temporarily deactivate all plugins if necessary. Then purge the LScache and then check the response header.