I have a WD EX4100 with 4 x 3TB drives installed in a RAID 5 configuration. It is currently working well and has the firmware update to version 2.41.121. The NAS was new in 2017 following a lightning strike that trashed my old EX4 box but thankfully the drives remained intact and I didn’t lose any data.
I only use this NAS as a file and media storage facility locally on my home network. I map the NAS folders through Windows. I don’t require remote access to it and don’t save any of the info to cloud services, as I have spare drives on a little-used PC and other external drives for backup. I have 3.9TB free space.
At some point, I do plan to access the music, photo and video files through my home LAN connected cinema setup, but I just haven’t got round to it yet.
I’m nervous of upgrading from OS 3 to OS 5. I have been reading on this forum about problems that others have had due to the upgrade and wondering quite frankly, is it worth the effort?
I’d appreciate your experience, both good and bad please, as I know there is no going back if I take the plunge. I believe that I would get no support from WD beyond April 2022 if I don’t upgrade, am I correct? What advantages would there be to upgrading? Apologies if a question like this has been posted before, but I didn’t find anything that answered this question.
Thanks in advance
Ed
OS/3 in 2020 is a notable security risk.
OS/5 is an attempt (in 2020) to (among other things) address the security risk. . . but at the cost some privacy and functionality (well, compared to OS/3 when it WD supported these units).
You can keep an OS/3 device on the network with reasonable safety IF you completely disable web access to the device (Firewall from the router; not “turn off cloud services” from the NAS. The issue relates to “backdoors” and other flaws in the OS/3 software)
Thanks very much for your comments, very helpful.
How would I introduce a firewall from the router to the NAS? Would this be something I would do through the NAS box admin login or would I do it through the PC in Windows? What would be the most suitable software please? I’m tech savvy but by no means experienced in these things.
Do I infer from your comments that it might be better to upgrade to OS/5 and lose some privacy and functionality rather than faff about with the firewall option? I would also keep support from WD if needed in the future.
Firewall should be implemented from the Router.
You would log into the router Admin dashboard to make this happen. Google your router to get model specific hints and instructions. The internet blocking of the base router firmware will be more than adequate.
My view: For most pedestrian needs: OS/5 is fine. However, WD is not known for their crackerjack device security. 
If I was buying a NAS today. . .I would look for a brand with a better rep. HOWEVER. . . .in the firmware released this week; it was notably rich in security updates. . . .which is a good sign.
Personally, I would be inclined to put OS/5 behind a firewall just like OS/3 - - → But I am a bit of a security nut. For most people it is fine.
Thanks very much for your help, I’m going to upgrade to OS/5.
I do not like os 5. I am primary sharing to my roku devices. In os3 there was media has a tab and one simply slide it to on for DLNA sharing to share from the WdMycloud. I could not upgrade my old device to os5. Therefore I really do not know what would occur if one were to do that. I ended up buying and returning a WdMycloud home then getting a MyCloud ex2 Ultra. When setting that up I found out I still needed twonky or plex or whatever. I got a variety and conflicting answers from support regarding what to do. A simple functionality was removed putting me in the hands of a third party. So who is the security risk from which I am being “protected ? Os 5 should have least maintained that ability. So I see it as a step backwards.
