I have a 2765 (non wireless) that was a office spare and had never been used. I have now powered it on, to be used, and after about 60 seconds the 2765 starts making an annoying whistling noise. This noises chatters slightly with network activity.

This is quite audible across the room where it is located. This was replacing an old but silent 2762, which we have had to put back until 2765 issues are sorted.

We have tried different Draytek power adapters, just in case the suppled power adapter was faulty, but no change, noise still present.

Anyone heard of this and any solutions (other than cover it with a pillow !!!) ?

This unit is effectively brand new and this it is really annoying, first time I have had any issues with many many Draytek units I have deployed.

Used a spectrum analyser on my phone and the 2765 is emitting two tones at about 7kHz and 9kHz. Not able to post a picture unfortunately.

In the end I returned the 2765 to the vendor for refund.

This was despite Draytek UK offering a replacement on a 30 month unit. Nice, thank you.

It has been replaced with a 2765ac unit, which is silent and works fine, as would be expected. Uptime is 130 days on a 500Mb fibre, no issues.