Will this shield actually work on our 802.11g routers with no support for b?
I have never heard of such a thing. Every consumer and enterprise grade wireless router I have ever used supported the current newest format, and all the previous ones. Usually through a setting called
. -Correction, "Mixed-Mode" is apparently a new term that deals with N devices, but the idea is the same. b/g/n are backwards compatible, and you can change this setting on the router.
Sounds like the router is misconfigured. It is common to disable b/g support on a router because it can slow the remaining faster devices down.