I installed Vcenter on my computer I was able to login in my computer with firstname.lastname@example.org, but on other computers or server when I tried to login I get this message "Incorrect name or password"
In the vCenter Server Management for example i can log in all on all the computers.
So you have installed vSphere vCenter on a VM (present on your computer). Correct?
Do you access the vCenter using the FQDN or the IP? Is the DNS server used the same both on the vCenter and on all clients (both your host from which you can access and also those from which you cannot access)?