I've heard good things about it, however I'm a bit dissapointed with TP-Link's 5Ghz configurations for Europe, they don't seem to make much use of the available channels which now means you end up stuck with 1 set of channels to use and everybody's routers seem to be using them...
I'm currently using an Archer C9, only reason my 5Ghz WiFi works fine is because I've got it setup as if its in America meaning it using channels 149 - 161, my only other choice using the United Kingdom settings would be 36 - 48 and they broadcast at a much lower power level than the one I'm using and all my neighbors routers are also using these channels.
Is there any reason you won't use the HH5B's built in modem and remove the modem... the HH5b I'm sure your aware is G.INP capable and the WiFi channels can be set at 100 - 128, if your HH5B's 5Ghz channel is currently set to 36 - 48 then change them manually to 100 or above, this will make the HH5B broadcast at a higher power output...
I've attached a picture which tell you the different transmit power levels of channels below.
Hope this helps