virtualbox.org

My host is Windows 11 running Virtualbox 6.1.26. The VM guest is Ubuntu. The network setting is bridge adapter. Both Windows host and Ubuntu VM has no problem accessing Internet. They can ping each other. I can do telnet (telnet VMipaddress port#) from window host to VM. But it time out if I do "telnet VMHostIPaddress port#) it timeout. I have a listener listening on the port number on both the Windows host and VM guest.

If I understand, you have full network and internet in the VM and host, and you can telnet into the VM from the host. But you cannot telnet into the host from the VM. Both host and VM have telnet listeners ready.

Have you opened the host's firewall for telnet? I'd wager that Windows Firewall blocks telnet by default.