My B593s had ancient Sonera branded firmware that has DNS issues when IPv6 is active. At least IPv6 reverse queries stall causing long delays. There's some rumors going that Sonera provides updated firmware over-the-air, but I couldn't trigger update despite trying hard. Might be because I was using Elisa SIM card. Since Elisa does have fairly recent firmware available for download I thought why not use Elisa firmware instead - get IPv6 bug fixed, have correct operator settings as default and also future updates should work without extra hacks.