I assume youre unable to ping the hosts? Are you able to access the DCUI and check the management network from there
If the management network looks correctly configured & youre able to ping the host then I would probably try restarting the management services, see VMware Knowledge Base
If you run into issues, check the hostd & vmkernel logs
If you have access to the DCUI, login with shell and check the following log files:
You can investigate last lines of each log file, for example with tail and then search for any possible keywords with grep , like error, failed and etc ...
tail -100 /var/log/syslog.log | grep -i failedPlease mark my comment as the Correct Answer if this solution resolved your problem