Can't fix gateway or detect non-working gateway in VirtualBox

[thejoelpatrol]

Guest OS: Windows 10 22H2 19045.2604
VM: VirtualBox 7.0.4 r154605
Virtualbox Guest Additions: 7.0.4
Fakenet Binary Release: 1.4.11
Expected Behavior: Fakenet changes gateway setting at startup, if necessary
Actual behavior: Fakenet can detect that the gateway is not set, but cannot set it, and cannot detect a case where the current gateway setting will not work.
These problems only occur in VirtualBox guests. The same guest image on VMWare works fine (with VMWare guest drivers and tools substituted for VirtualBox's, obviously).

Case 1: Gateway not set
Fakenet detects this but can't fix it.

Case 2: Current gateway setting does not work (x.x.x.1), Fakenet doesn't notice.
Unclear why x.x.x.1 does not work but x.x.x.100 does work.
Fakenet responds with ICMP errors in this case.

Case 3: Gateway setting is OK (x.x.x.100)
Fakenet works as expected.