I run Roon Core on a NUC using ROCK.
I installed Roon Extension Manager (REM) on a rpi4 that I use for some network management. It works great and I have discovered a bunch of interesting extensions I didn’t know existed.
My question is how does this all work. Specifically:
1- Does REM serve as a software repository only?
2- Once I chose an extension and install it does it load onto the Core and run there? Or does it need the REM to handle tasks live?
It always needs REM to be running elsewhere. I run a VM of DietPi (the OS I find the easiest to use with REM since it is pre-installed and just a toggle in settings to activate) on one of my Windows PCs.
I did check that REM disappears when not running.
Are you saying that installed extensions, when they run, need REM to be running?
(I could of course check myself but I am at work right now).
More importantly, if REM needs to be running when an extension is used, it seems some of the work is done in the remote machine… Is this the case?
On extension manager’s github page it says
… remember that extensions are installed on the device at which the Extension Manager is running …
so extensions run on the device where the manager is installed.
Ok, thx. That was my question. I read the info on REM trying to piece this out, didn’t see that.
So, with a Windows, Mac, or Linux PC you can get the extension manager to run in some way on the same machine as RoonServer. ROCK (and nucleus) is locked down and you have to run it all on a different device. I used to use my Allo DigiOne player (which is running DietPI) to also run REM and the extensions. But, that got put away in a move and since I’ve been using the DietPi VM I mentioned above.
Ok understood. I am running REM on a rpi4 that I run some other networking software on.
I have a noob question. I have a homebridge server on RPI4 up and running 24/7. Is it possible to add RME and extensions on this machine? Homebridge is Linux and node.js LTS is working due to it’s needed for Hue bulbs for example.
Sure, go right ahead!
(And you did mean to abbreviate Roon Extension Manager, right?)
Thanks! Yes, I meant Roon Extension manager.
I will try my very best. I am sure a lot of googling will be necessary… 
I was installing macro.on on my Mac and found it very cool. But the Mac isn’t running all the time.
Yes you can. I have an rpi4 running the Unifi controller for my home network and it was no problem at all to add REM to that.
What specs does the RPi4 need to have? Like memory etc?
And did you install REM using the instructions for Linux on this page? Of not, what instructions did you use? Thank you.
Whatever RPi4 you can get, doesn’t matter really.
Easiest would be going with DietPi, then use it’s software install menu and select REM.
Why not use rooExtend?
because I guess I know nothing about it.
Ah, I see 
rooExtend is a ready to run SD-Card image with preinstalled Roon Bridge, REM and some commercial Roon Extensions I provide. You also can connect a HDMI TV to display Roon artwork.
REM, Roon Bridge and TV output can be used for free. The Roon Extensions I provide need a License Key.
For more information please visit http://diy.rooExtend.com and also this thread for general questions.
Each of my Roon Extensions also has separate thread you cannfind if youn
search the forum for rooExtend.
Best DrCWO
Did not see a direct thread for this. Recently set up a pi with the rooextend. I will in the near future be purchasing some license. In the mean time I can’t see the “chrome” for display. I’m sure I’m doing something wrong.
Here I can help. This is my main rooExtend tread. From there you have a lot of links to the threads to all of my Roon Extensions.
The DIY page can be found at http://diy.rooExtend.com. There you also find a link to my download area to get the latest rooExtend for ARMv8.
If you like to get a Plug&Play product please visit https://rooExtend.com
If you connect a screen via HDMI to a Pi3/4 with rooExtend you will see the Roon Logo at the screen after enabling the rooExtend Roon Extension in Roon Settings/Extensions. The ZeroW2 does not support HDMI Roon output.
Best DrCWO
I have the hdmi out connected to my receiver. Does it have to be directly connected to a screen?
Please try directly with the screen. If I remember correctly, another user reported that connecting via a receiver did not work.
The screen must be connected before booting!
Best DrCWO