Plex Without Internet

Is there any tech guy have sound knowledge to solution this query:-
“WD my cloud Ex2 Ultra and wireless-router connected with LAN” (Direct connection), Internet not available on router.
Mobile and Laptop connected to router via wireless- router, same network (Internet not available).
Plex and other required application pre-installed on cloud device.
WD my cloud Ex2 Ultra has cloud OS3 and created multiple login credentials for user.
How can access WD my cloud Ex2 Ultra using login credential from laptop and mobile without using internet?
Which application can be use to access files? Explain briefly.
Thank you.

Hi everyone. Forgive me if this was covered somewhere, but doing a search did not find it.

Does anyone know a dongle device that can have Plex installed on it and stream from a local network WITHOUT internet? I have a WD wifi hard drive that has Plex media server on it. This works well when camping and the kids can just jump on the network that the WD has and use the Plex app on their iPads. Watch now without any payment or subscription. Plex Media Server is the software that allows you to stream your content to all of your devices, anywhere. Internet connectivity is at the heart of the Plex experience Media Server, but that doesn't mean there are times (like during local outages or while on vacation away from reliable Internet access), you should do without Plex. Keep reading while we show you how to change things (and why it's important to set them up before you need offline access). One of thethings that people love most about Plex is the streamlining of the experience, and that streamlining is centered on their Plex accounts. Apr 19, 2017 - Internet connectivity is the heart of the Plex Media Server experience, but that doesn’t mean there are times (like during local outages or while vacationing away from reliable internet access) you need to go without Plex. Read on as we show you how to tweak things (and why it’s important to set things up before you ne.

I have a Roku 2 XS that I got last August. It has worked perfectly and given me no trouble. I have used it for Netflix, and also to stream video from Plex installed on my Mac via a direct Ethernet connecting between my Mac and a cable router. I did not use Wifi for the Roku.
Recently I canceled my Comcast Triple Play account because it almost doubled in price. I never watched the cable TV, so my plan is to just have broadband internet access, but at the moment my only internet access is via a personal hotspot via my iPhone.
What I'm trying to do, is what I have been doing since last year, which is to stream video from my Mac to the Roku via ethernet from Plex. However, now that I do not have internet access this is not working! Plex starts up, but all I get is the preference screen. It sees my Plex Media Server on my iMac, but nothing happens. The Roku also sees the local network, and the fact that there is no internet. But Plex wont load my media.
It was working while I still had the Comcast modem, which I was using as an ethernet hub without Internet access. But I returned that, and tried connecting the Roku directly to my iMac. Didn't work. So I used an Apple AirPort Extreme Wifi router between my Mac and the Roku, just as an ethernet router. That also didn't work. Last night I got that setup to work only as long as my iPhone was connected to my Mac via USB as a personal hotspot. I didn't understand why that was needed, since I was not accessing the Internet, but it did work.
Today that setup doesn't work. Plex
So my question is, how do you use the Roku to stream video from Plex on my computer via ethernet with no Internet connection? I don't see why Internet is needed for this. It seems dumb that everything needs to be connected to the Internet in order for it to work. I'm not trying to stream stuff from Netflix or other online sites, just from my Mac via Plex. I will have a new internet account soon, but I see no reason why this shouldn't work.

Plex Without Internet Reddit

Other details; it's an older SD CRT TV, so it does not have internet connectivity. That's why I got the Roku, which replaced using an X-Box 360 for Netflix.
I did go to the secret home screen on the Roku and turned off pinging, as I read someone suggesting to do. As I said, the Roku sees my local network just fine. It also sees my two wireless networks (the iMac and Airport) which are set for Internet sharing, and which work to my son's Mac Book Pro laptop, and worked last night. We watched a few videos via Plex, but tonight it doesn't work.

Plex No Internet Connection Error

Using Plex Without Internet

So, any tricks for using the Roku on a local network only, with no Internet? And if not, that's a really stupid thing for Roku to do.