I think you are confusing things here.
Asuswrt is the firmware developed by Asus - this is what you have on your router.
Asuswrt-Merlin (there is no MerlinWRT) is a third party firmware intended for Asus routers. At the time I'm writing this there is still no public release of Asuswrt-Merlin for the RT-AC87U.
Oops sorry for confusing you... yep aware that I am running AsusWRT
Is anyone one else facing the problem I mentioned ?