Thanks for your help in this matter Josh.
I tried the above but there was no improvement.
My husband downloaded a speed test to the phone and we established that the ping and download speed are fine, but the upload speed starts quite quick and then slows right down and around 77% stops for quite a while. We suspect this has something to do with the problem.
I can't send the phone to sony as I don't have a replacement to use in its absence and am heavily reliant on my phone for business reasons, so I imagine I'll end up getting hold of a Samsung as my husband's works fine and selling the Xperia. Such a pity, this is a beautiful phone and great in all other ways but letting itself down massively in the wifi connection for me.
Originally Posted by Josh-SonyXperia
Have you tried updating the phone or the Repair Phone option on PC Companion? If you did then the only option would be to contact your local Sony Mobile office for info on how to send the phone to the repair center for an evaluation. Try this list to get the appropriate phone number to call
Contact info – global contacts - Sony Smartphones (US)