@David-TP 

Hi David, the problem with using that Beta firmware (1.5.1 for the S4) is that it is very old now and is missing some of the key recent security updates. In fact having some awareness of the current level of security threats out there I find it very worrying that TP Link are recommending people use these older firmwares as it clearly puts people's devices at risk. I would strongly recommend users keep their firmware up to date to best protect their home network and I would have thought that TP Link would also recommend the same.