Update 2018-Dec-11: I’ve spoken to a LoD team member and to jump straight to the point of you have a LTE Tab S4 then simply put the required update isn’t available at this time and there is no information on when it will be available.
Some people trying to install Linux on Dex are running into an obstacle. After installing he app and trying to run it they get the following error message.
Linux on Dex requires your device to have the latest software o support some features.
After this message is acknowledge the application closes. If someone with this error checks for updates in the app store or for updates to the operating system they get notification that everything is up to date. What’s going on? I contacted LoD support about this and got back the following response.
Currently, the Linux on DeX(beta) requires latest SW for Galaxy Note9 and Galaxy Tab S4.
SW update schedule may vary depends on the region and carrier.
What does this mean? It means that your device doesn’t have a update that is required for DeX and that your carrier might not have released it. Devices sold through a carrier can be a bit slower in receiving their updates. Samsung hasn’t been specific on the updated needed. I’ve communicated with someone on the Linux on Dex team and was told that LTE tablets in general do not have the update that is required for Linux on Dex. Additionally the person told me that there is no information available on when particular updates will work their way through certain carriers.
BTW: Unlocking your device and installing a SIM from another carrier will not change this; this behaviour is dependent on the carrier for which the device was made, not on the SIM that happens to be in the device at the time.
j2i.net 
It appears to be incorrect. I have the October security update and still getting the same message. Maybe it does not work on carrier branded devices. Mine is Telcel Mexico.
Hmmm…okay, since it sounds like I am incorrect I will remove this post. But I’ve also heard from people with carrier branded devices for which it has worked. I guess the exact requirements may be publically unknown…
Do you know the build number on your device? Talking to some others it sounds like build ARJ5 may be needed.
I spoke with someone in the LoD support team. The person is telling me that none of the LTE tablets out now have the necessary update and that there is no time estimate on when it will be out. I’ve updated my post accordingly.
I’m not on a carrier, I bought it outright and I’m getting this problem.
I can confirm that the Verizon Tab S4 is not working with its latest ARI4 update (released Oct 16). Boo!
I updated my post. Someone at LoD support tells me the update isn’t out on any LTE versions of the tablet yet.
I have the LTE version of galaxy tab s4 and still have not received any update.
If you are on an LTE/Carrier device the problem is that the carrier hasn’t released the updated yet. I sent a note to LoD support and they told me that none of the carriers have released the update yet. If you’ve recently received the LoD survey I encourage replying to it. One of the data points on they survey was about people that wanted to try the beta but cannot due to not having the required updates.
Would love to know what the required data is, since my TMO S4 updated to the Dec 1 security patch level, and that’s not it…
That makes too of us. I had a breif moment of excitement when I saw the updated followed by disappointment. I’m sure you experienced the same thing.
Required update, that is.