Thanks for the clarification, tom89. We would like to arrange a call from one of our Technicians for further investigation and real-time testing. Let us know your account details (Username/Customer ID) together with your best contact number and preferred time.
Did you ever get this resolved?
I am on my third TPLink VR 1600 all with the same problem (TPG insisted I swap each time), including an engineer visit who also confirmed the issue on the 5Ghz network.
At this point TPG are refusing to provide a different make/model or assist further.
We normally suggest to use 5GHz since it transmits data at a faster speed than that of 2.4GHz. However, the range is shorter for 5GHz and some older devices may not be compatible with it. So as a general rule, if your devices can detect 5GHz, then go for that band. Else, pick 2.4GHz as a last resort.