Please try again with ICE=force instead of force_relay, or (more
conservatively) ICE=remove in the offer and ICE=force in the answer. You
will probably also need the option "rtcp-mux-demux" in the offer, as
your non-RTC endpoint doesn't support rtcp-mux and Chrome isn't likely
to be happy with its rtcp-mux offer being declined.
Alexey Rybalko writes:
There is no such attribute in SDP payload from the latest Mozilla (v.29).
there *is* a=setup:actpass in above.