Something that has taken me some time to debug: session_set_cookie_params() does not work when the domain param is just a one level domain, like it was a TLD.
I have a site in an intranet and our internal domain is .local, so trying to set the cookie session to the .local domain does not work:
session_set_cookie_params(0, '/', '.local'); // Does not work
In all test I've done, setting the domain only works for SLDs and above:
session_set_cookie_params(0 , '/', '.sld.local'); Does work
This is nothing to do with PHP but the http protocol, witch does not permit setting cookies for TLDs for obvious security reasons.
