Two hours should be more than sufficient at FRA.
Personally I would not book anything under one hour in FRA. (more if you need to pick up and re-check bags!)
Standard MCT is 45 mins in FRA with quite a few exceptions at 60 mins or even 75 mins.
[KVS Availability Tool 5.1.0/Diamond - Reference: Minimum Connection Time [MCT]: FRA]
Code:
** EXCEPTIONS EXIST **
DD DI ID II
STANDARD: FRA 045 045 045 045