easy:SetOpt_Happy_Eyeballs_Timeout_MS(timeout)
timeout
milliseconds. If the IPv6 address cannot be connected to within that time then
a connection attempt is made to the IPv4 address in parallel. The first
connection to be established is the one that is used.
The range of suggested useful values for timeout
is limited. Happy
Eyeballs RFC 6555 says "It is RECOMMENDED that connection attempts be paced
150-250 ms apart to balance human factors against network load." libcurl
currently defaults to 200 ms. Firefox and Chrome currently default to 300 ms.