Hi. Maybe you can change the ADSL mode of TD-8840T to ADSL2+, ADSL2, G.DMT or the others for a try.

reenag06 wrote I have managed to connect to the wireless network for my mobile phone and printer but it still wont let me connect wirelss to my laptop, it only works if I have the ethernet cable...

Hi. Have you tried to change the channel on the modem? If you have tried that and the problem still persists, before you switch off and on the wifi button, can the computer access Internet by wired...

20/40 MHz is the default settings for Channel Bandwidth. You cannot change it to 20MHz??? And I also find a beta firmware for TD-W8951ND_ V5 on TP-Link website, you can upgrade it for a try....

Hi. I find some instructions about Bandwidth Control in the Page 84-86 of User Guide: http://www.tplink.com/Resources/document/TD-W8970_V1_User_Guide.pdf

sharno wrote There's always an error with Apple devices .. I have a mac book pro too and it took me a while to get it connected through diagnostics and assistant. I don't know why it's not easy...