Just to add…
I bought a 3TB My Cloud Home and tried to install it today.
It too detected the device and showed the ID code, but clicking the connect button returned the rather unhelpful Unknown Error. Please try again message.
I called WD support.
I spent 75 minutes on the phone, going backwards and forwards between my PC and the My Cloud unit (located on different floors).
Downloaded WD Discovery software; Rebooted / Reset my Cloud unit; Disabled Windows Defender Firewall; Disabled McAfee Total Protection; Restarted PC; Tried to connect using a different PC with no Anti Virus software on it.
I went into the Router settings and could see it was there, but it wouldn’t communicate with either PC.
The WD support person advised that I had two options, escalate or return the device to the retailer.
I asked if support could be done remotely, so they can see and adjust any settings needed, but was told they don’t do remote access support.
I’m returning it back to the shop this evening. Unsure whether to exchange and try another or just get a refund.
As others are having the same problem just now, I may just take the refund.