USB not visible - why?

[Ubiquitous2024]

My desktop > phone connection is always intermittent, this has been going on for years with different phones and desktops. You get months of no issues whereby phone plugs in, files open on the desktop and you can transfer files / music whatever. Then for absolutely no reason whatsoever, it suddenly just doesn't work. Phone says "slow charging, make sure cable isn't damaged or defective" and it doesn't work. Absolutely nothing changes between it working and not working. Then you go through tons of different cables, try tons of different ports, but it remains invisible. Then suddenly at a random time in the future, it will work again?

I have been trying for 2 days now and still can't get visibility of my phone on the desktop,

Why does this happen?

[Mr Squarekins]

Might be stating the obvious, but I know when going the same, my phone has to be 'active'. If the phone isn't live with an active screen, my PC does not see it.

[lufbramatt]

Fluff in the phones charger port?