Oh, now this is interesting. I've got it working now, but I'm not sure if it will continue to work through a reboot.
What I've done is:
- Notice that the driver I linked to above is version 17.3, but the Intel Ethernet Connections CD version is 17.4, so I downloaded that and installed the newer driver from that CD. I'm now running 126.96.36.199.
- Re-created my VLAN 91 and Untagged VLAN interfaces. Still no network connectivity.
- Individually disabled and then re-enabled the two newly created network interfaces. I hadn't tried this before. They both came up with network access!
- Disabled and then re-enabled the main Ethernet interface, the one in which the two VLAN interfaces are configured. This caused the two interfaces to disable and then re-enable, and they no longer have network access.
- Step 3 again, individually disabled and re-enabled the two VLAN interfaces. Now I have network access on both VLAN interfaces, I can reach devices on both networks, everything seems fine.
I'm concerned about step 4 above, and wondering if that means that after I reboot the laptop, the two VLAN interfaces will have no connectivity until I explicitly disable and re-enable them.