virtualbox.org

Host: Windows 10 Enterprise 1909
Guest: Ubuntu Desktop 20.04
VirtualBox: 6.1.6 r 140961

Configuration:

1. The Ubuntu guest is able to communicate to the Internet via default NAT network.
2. The Ubuntu gest has an IP of 192.168.56.101 from 'ip address'. (I haven't figured-out the guest-host clipboard thing yet to be able to include the output from 'ip address'.)
3. The Windows host has an IP of 192.168.56.1
Ethernet adapter VirtualBox Host-Only Network: Connection-specific DNS Suffix . : IPv4 Address. . . . . . . . . . . : 192.168.56.1 Subnet Mask . . . . . . . . . . . : 255.255.255.0 Default Gateway . . . . . . . . . :
4. The Ubuntu guest can ping 192.168.56.101, but cannot ping 192.168.56.1.
5. The Windows host can ping 192.168.56.1, but not ping 192.168.56.101.
6. Using this link (stoopid rule about not being able to post urls) I can confirm that ufw does allow ICMP.

Because this is a a heavily restricted environment I don't have local admin access (requesting and getting it requires VP approval, even temporarily). I want to eliminate the obvious or silly things before getting the help desk involved.

What are the obvious or silly things I should be looking at?

That sort of problem is usually a client firewall problem. Do you have enough privilege in Windows to disable or modify the Windows firewall on the host?