I found this thread in this forum.

https://www.giantbomb.com/playstation-4/3045-146/forums/could-use-some-help-with-ps4-rest-mode-issue-1879455/

However, none of the proposed solutions in here help me.

I have a Crucial X8 SSD:

https://www.crucial.com/products/ssd/x8-portable-ssd

The thing, every time upon waking the PS4 Pro from Rest Mode I get the error message that the drive was improperly disconnected, etc. etc. I just have to click "OK" and "Yes" and I am good-to-go. No data issues. I have the Rest Mode setting to supply power to USB "Always".

It's just annoying because I cannot remotely download any games because the PS4 thinks that it is disconnected and will DL to the internal HDD. I also cannot suspend any games for the same reason, i.e. the PS4 thinks it's disconnected. And, I guess, in a way it was momentarily disconnected. While troubleshooting with Crucial Customer Support, they had me trying connecting my phone to the USB ports of the PS4 and putting it into Rest Mode. There is a momentary period of time during the "transition" where the system stops supplying power to the USB, before it begins again. I think that the SSD loses power for the brief moment and the PS4 interprets that as it being disconnected. I tested out an old HDD that I used to use without issue with my old base PS4, and it did not experience this artificial/temporary disconnect issue. I had posted on other forums as well and someone just recently replied that they were also experiencing the same issue with the same model of SSD.

I guess absent some kind of solution, I might want to look into another SSD. Granted PS5 is coming soon. I get it. I am wondering if anyone else uses an external SSD and experiences this same issue. If not, would you mind telling me what model you have so that I can look into possibly purchasing it? Or, does anyone know of any causes and solutions to my current set up?

Currently have my eyes on these:

https://www.amazon.com/dp/B073GZBT36/?coliid=I9BTC6G4OJ03T&colid=28CBWHP62HJYY&psc=1&ref_=lv_ov_lig_dp_it

https://www.amazon.com/dp/B07C5BG857/?coliid=I2OX35M5B6AKMX&colid=28CBWHP62HJYY&psc=1&ref_=lv_ov_lig_dp_it

Don't want to buy a new one, though, if the exact same issue is going to arise.

@igrac: I have the similar problem with yours and haven’t found any solution too. I have the PS4 slim model, and the X8 SSD keeps on disconnecting whenever it woke up from rest mode.

I have tried changing the cable, switching to different port, same issue. USB is also set to always be powered on on rest mode.

I also tried to charge my phone(an iPhone X) and set the PS4 into rest mode while its charging. In my case, the iPhone stopped charging completely while on rest mode. However, tried charging my controller and it charge just fine on rest mode.

My assumption is that the iPhone & X8 SSD is simply drawing too much power for the PS4 Rest mode to handle. Hence it always powered off when put on rest mode. The issue might be this SSD model.

Note: I saw another user in reddit who is experiencing the same problem too earlier. Using the same SSD.

That's me. ;)