When dealing with NDIS IM drivers you should sign both CAT file and driver binaries (embedded signing).
Normally all WAN connections in Windows go through the NDISWANIP (for IPv4)/NDISWANIPV6 (for IPv6) Ethernet 802.3 emulation on top of WAN miniports. So if you need to filter packets going through WAN connection you are supposed to filter on NDISWANIP (or NDISWANIPV6) network adapter listed by listadapters.
Update:
ndisrd.inf describes protocol part of NDIS IM driver and installed with hidden attribute.