Steel windows and wireless

Wireless broadband is marginal here, viz. fails for 5 min.
to 12 hours once a month or so, and no one knows why
(est. 1 or 1.5 miles to the nearest cell phone tower.)

As soon as vinyl (-clad steel) windows were installed,
replacing all-wood windows, reception became no good
(ISP's wireless modem scanning all the time without
ever locking to a signal.) Do steel windows create a
sort of Faraday cage preventing connection?

--
Don Phillipson
Carlsbad Springs
(Ottawa, Canada)