iPhone 4s stuck on serching...

Hello i got iPhone 4s 16GB with ee uk sim lock and i have an problem with geting signal, phone keeps serching and sonetimes after a long times it display no service. I got ee uk card but im living in Poland. Phone workt before with rsim 8 but i dont know why it starts displaying serching... Same with original sim i tried hard restet, installing fresh ios from DFU mode and resetimg network settings. Fun fact is when im switch carier settings from automatic to manual it will display cariers propely but wont connect to any and i dont know why i cant get to carier option in iOS 8. Please help because i have no idea what to do next.