The vpxa service communicates between the vpxd service on vCenter and the hostd service on ESX host, and if vpxa goes down, vCenter considers hosts as unresponsive.
VCF Operations 9.x
/etc/init.d/hostd status/etc/init.d/hostd startFor any config_issues in vpxa, retrieve the vpxa health report by logging into the ESXi host.
$ localcli system health report get -r vmw.vpxaStatus
From this health report, look at the config_issues and any configuration update issues and the connected_to_hostd field for vpxa-hostd connectivity.