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Can we use wireless access point with HWIC-4ESW card installed in a 1841 router
I don't know if you'll have seen my reply to your other post in the WAN Routing + Switching forum, so here it is again :-
I don't see any reason why not, though you won't get Power-over-Ethernet from the 4ESW - you'll need a power injector or a mains adapter for your access point in order for it to power up.
Hope this helps!