I'm a non-EU citizen. 32 years of age. I did my Masters in IT (3 years) from Germany. After my Masters i've been on a BlueCard visa (3.5+ years). I'm currently eligible for a Permanent Residence (Niederlassungserlaubnis). Due to some family reasons, I will have to stay outside of Germany for more than 6 months (probably even longer).
Can someone please guide me (or preferably point me to the law) on how long can I stay outside of Germany without losing my PR status? Do I need to keep an address in Germany during that time period?