As posted above, take the airside shuttle bus from 2G to 2E; don't exit terminal 2G! Just follow the signs for terminal 2E. You have to pass passport control there in terminal 2G before boarding the bus, then about 12 minutes driving (S3 is the first stop, but check your gate in the waiting area before boarding the bus) and no security control anymore in 2E, that's the good part of it. 90 minutes is plenty of time, don't worry. My last connection was 45 minutes and I made it (just in time).