Sorry to resurrect an old thread, this is just an FYI - I've got 2 units, an original 800Mhz unit, and a more recent 1000Mhz unit which is badged as an AC1900.
The 800Mhz unit is setup as an AiMesh node and it overclocks to 1200,666 just fine.
The 1000Mhz unit refuses to overclock beyond its...