I had a set up with a powered external hard drive, and a wifi dongle. It worked fine.
One day, the wifi dongle decided to cut out—it would restart every time I inserted it into the Pi, and after the restart, the Pi would not recognise it. I since replaced this with another one that works.
I wanted to replace the powered external hard drive with a portable one, that does not use an external power supply. I have three of these, one of which can use an extra USB port for extra power. All three of these restart the Pi, even if the one requiring extra power is powered from a port separate from the Pi. After the restart, the Pi will not recognise any of the devices, nor will it recognise the wifi (working dongle).
One hard drive has a power light that is easy to see, and when it is restarted with the Pi, the light oscillates between off and on. It will do this for around 30 seconds, after which, it remains off.
I read that the Pi can have issues providing the initial power to such devices, and that it can be fixed by adding a capacitor. However, I also read that the devices should work if started up with the Pi, which they don't. Is the issue likely to be that my Pi has somehow become faulty, and won't give enough power, or is it worth adding the capacitor (or another solution)?
Thanks for reading!