In the screenshots we saw above the host was named “TestHost1”. The output you are showing is for a host called “esxi1”. It looks like that is not a hostname that is resolved by dns, so you are getting the Name or service not known error.
Which command did you run to get that output and did you change the name of you ESX host in the webinterface?
If you ESX host is still called “TestHost1” in checkmk, please try to run cmk --debug -nvv TestHost1 as the site user and see if that spits out an error.