My TP Link AC 1750 ADSL2+ modem seems to have developed a fault whereby the power light is on (and remains on constantly), but every few seconds the wifi light will come on then go off; shortly followed by all of the lights coming on and then going off again. This series of activity repeats every 30 seconds or so. It doesn't look like a power problem, as the power light is on continually.

When connecting directly to a laptop I'm getting a similar picture, in that the latpop will briefly recognise an ethernet connection (e.g. laptop connected via ethernet cable to the LAN port on router) but this drops every time the cycle repeats. I'm trying to use the AC1750 as an access point / repeater, hence it is not plugged in to a telephone line.

I've tried a factory reset, and th suggested 30|30|30 reset, and am now out of ideas.

Any help gratefully appreciated.