Hello I have the My Cloud First Generation , which I already know support is ending anyday now. (April something) . Anyways am I correct in saying that these cannot be hooked up to a computer and used as an external HD ?
Correct.
These devices are NOT designed to be used as an external HDD. (there is some trickery you can do to hook it up via a network cable; but I don’t recommend it)
The device however CAN still be used as a NAS. . . .but you need to block all internet access to the device. OS/3 has numerous security flaws, and should not be exposed to the internet.
When I say “block all access”; I do NOT mean turn off cloud services. What I mean is that you need to go into the ROUTER’s configuration dashboard, and block all internet traffic to the MyCloud device. This won’t make the device invulnerable (since something can worm it’s way into your network via a PC); but it will be pretty decent protection.
To be honest. . . . I actually recommend the same for devices on OS/5 
note: with internet access blocked, you can usually still reach the device if you log onto your home network remotely using a VPN. (I say usually, because in some cases when you block internet access; you often will also block access via different subnets WITHIN your network. . .and that would block the VPN connection to the device)
I have mine setup as network storage. See image below. I changed the address to static. I disconnected from the internet.
Click on, tap, or activate image to enlarge it.
Look at my prior post.
WDMYCLOUD 1st Generation now on my Network only - My Cloud OS 3 Personal Cloud Storage / My Cloud - WD Community
All topics and post for the WD My Cloud OS3 should be in that sub-forum!
Latest My Cloud OS 3 Personal Cloud Storage topics - WD Community
You cannot connect a My Cloud’s USB port to a computer and use the My Cloud like an external hard drive. What you can do is connect the My Cloud Ethernet networking port to a computer that has a Ethernet networking port if you want direct access. But really its just better to leave the My Cloud connected to the local network so all devices can access it on the local network. After the shutdown of support on April 15th one should access the My Cloud Dashboard > Settings and disable Remote Access/Cloud Access. One should also disable internet/broadband access to the My Cloud at the router firewall level if one’s router supports blocking internet access by individual network client.
My Cloud OS3 End of Service
https://www.westerndigital.com/support/software/my-cloud-os/os3/os3-eos
Q: Will my device stop working if I can’t upgrade to My Cloud OS 5? Will I lose access to my data?
A: Once the services have been shut down, you will still be able to access the device on a local network. However, access through the My Cloud OS 3 mobile app or web app will not be possible. Email notifications also won’t be delivered. Devices that have auto-update enabled will receive a final firmware update to disable remote access and outbound traffic to cloud services. Then, support will end and you’ll have to use the local network to access the device.
Note: the first gen single bay My Cloud does not support OS5 (the topic of this subforum). There is a dedicated OS3 My Cloud subforum where discussions on the first gen single bay My Cloud are more appropriate.
OS3 My Cloud
https://community.wd.com/c/personal-cloud-storage/wd-my-cloud/105
