navigation system error

[xrider]

hello everyone.. need some help / advice here.. sometimes my p4p says "cannot fly - navigation system error - check redundancy state" .. so ive checked.. all in green but rear lights are red.. ive sent it in for check and drone was fine according to dji.. sometimes it seems easy to find sattelites.. sometimes it does not lock and i have to climb up to several feet to have a gps lock.. whats next?? how can i check it and find a solution??

thanks in advance
xrider

ps. downgrading didnt make any difference at all..