D6400 keeps dropping wifi internet connection

[Frank17]

My D6400 router is 8 months old. It has recently started dropping internet access for wifi connections - the wifi connection (from iPad and PC devices) remains (so it is possible to eg log in to the router) but without internet access. Wired internet access is not affected. Problem occurs in both the 2.4GHz and 5GHz bands. Upgrading firmware to 1.0.0.60 makes no difference.

Suggestions please?

[michaelkenward]

Tried different channels? Some people find that it helps to turn off the Auto setting for wifi channels.