Noisy router

Hi All, noticed over the last week or so, especially late at night, when I am scrolling through Reddit on my phone attached to wifi, you can hear he router processing the data with a high pitch noise.
I have never noticed this with previous FTTC routers over the years, just this [censored] Adtran 854-6 provided by Be Fibre on the FTTP service. I have mentioned in a previous post regarding the "Beyond basic router".

Do other FTTP users have this issue? It's not a cooling fan, I know that much. I don't notice it when watching a movie on tv over ethernet, tried using iPlayer on the phone get the same noise, but I get no noise from the 2 kids xbox ones being online, laptops or tv boxes.
Be interested to hear from others if they have the same issues.

LB

Power supply probably.

It's probably 'coil whine' from an inductor or choke. It can be annoying but is rarely a sign of impending failure. It will vary depending on router CPU load.

The one consistent seems to be your phone. I would say the phone isn't practically well shielded and is picking up interference

Hi All, thanks for the replies.
Just annoying more than anything
LB