Occasionally my PS3 refuses to sign in.? After trawling through a billion pages I finally found the solution.

Change your DNS servers to 208.67.222.222 or/and 208.67.220.220

All the other settings don’t really make any difference.? My router was even set up to put the PS3 in DMZ (Demilitarised Zone) which didn’t help at all. ? The fault really lies with your ISP, apparently.? My original DNS was 4.2.2.1 and 4.2.2.2.

Thanks to amstel78 from the PSN forums.