Hi @TszLung,    Welcome to TPG Community!    I've located your account using your Community details and was able to complete series of tests. .   I've seen a potential physical fault on the results and we need to do further assessment to narrow down and identify the possible cause of this concern.    I would recommend to have one of our technicians reach you to carry out further checks.    Please PM us your best contact time and number and we'll arrange this for you.    For your reference, please view this link on how send a PM.   Regards,  ... View more