Why do you upgrade the firmware? As frismo mentioned, the modem is locked by ISP. If yours are the same, try to contact your ISP and ask for help.

There s no RJ45 cable port in my router, its only for ADSL(RJ11). Router refers to W8901N? It has one RJ11 port and four RJ45 ports. I have conected the BSNL(ISP) Wimax CPE s ethernet cable to one of...

It seems that current firmware of your W8968 is the latest version. http://www.tp-link.com/en/download/TD-W8968_V3.html#Firmware Try to disable UPnP to see if it helps. If not, maybe it is a faulty...

How often do you power off and power on the M7350? If it a brand new device, you may take it back to the shop and have a test. Sounds abnormal.

When it loses connection, how about status of all lights on W8968? Can you login its web interface? What's the hardware version and firmware version of your W8968? Did you upgrade the latest firmware?

What a long post...lol... It seems that you haven't tried to connect the fibre modem directly to your PC bypassing any router. You may try if it works. If it doesn't work, I'm afraid that what...