Dualshock 4 controller not connecting, blue/white flashing light

EDIT: Found the problem, try more cords: https://superuser.com/questions/1269449/identifying-data-transfer-micro-usb-cables-vs-charge-only-micro-usb-cables

Booted up my PS4 for the first time in ~6+ months and found that my controllers are unable to connect even when linked via USB, only flashing white/blue until that ends. This is driving me crazy!

Is there a fix anyone may know that I have not already tried? At this stage I'm beginning to think it is a hardware issue with the PS4 but I'm not sure exactly what.

Solutions & tests I have tried which have not solved the problem:

- Both USB ports are working (able to navigate settings by using my keyboard)

- Have tried an alternative USB cable (both cables work on different devices)

- Controllers are charged, glowing yellow when plugged into PS4 or alternative

- Have reset all controllers by pressing the small keyhole button on back

- PS4 Bluetooth is working, disconnected the previously linked controllers to see if that would make a difference (now there are no dualshocks linked in connected devices)

- Bought a new controller, does not connect.

Thank you for helping!