Plex Media Server in the Car

First let me apologize if this is in the wrong Forum. I have been searching for weeks now trying to find a solution to this problem.
I have a plex pass and a plex server running in my house - no issues as there is an internet connection always.
The problem I seem to be having now is that we are taking a road trip for 2 weeks where there will be no internet connection. I have purchased a new laptop and installed Plex Media Server on the laptop. I have a standard router that is also going to be in the car - I have the Plex Media server up and running on the laptop and connected to the router in the car. However all of the devices Iphones/Android tablets and phones will not detect the Plex Server - it just says offline. If I connect the car laptop to the house internet and then open the plex apps - the app sees the server and it works fine. I have tried many different settings to get it to work but nothing seems to work unless there is an internet connection. I have disable require authentication - I have listed the ip addresses and subnet masks into the network setting section on the server settings - still will not work without a live internet connection.

Any ideas how to make it work?
Thanks in advance

Are you able to load plex web via ip while offline?

So assuming, while connected to the offline router your laptop has the ip 192.168.1.2,
What happens if you connect a tablet to that router and hit the laptop directly via:
http://192.168.1.2:32400/web/index.html?

If this works, you can manually add this server to the devices via Settings > advanced > server connections (ios).
NOTE: It may give you a page that says: 404 not found. If its rendered by plex, the manual server add should still work not sure though.

If this doesn’t work, I would suspect your router is configured improperly. There could also be a firewall issue on your laptop preventing port 32400 from being accessible to non-localhost addresses. This would still work with an internet connection because plex can map to a high port that is already open and usually not firewalled but, afaik it will not do anything like this on a LAN without internet.

I haven’t played with the ip’s and subnet masks much but for what you are trying to do it shouldn’t be necessary.

Laptop is brand new out of the box - Windows 10 (so that might be an issue) I will check the Windows Firewall setting tonight and report back.
I hadn’t thought of trying to see if the tablet would load VIA the webpage - I will also check this tonight and report back.
Thanks for your response - I’ll revert back tonight (hopefully with positive news)

Okay so logging the server out of the Plex Pass account and disabling the Plex Home features (Thanks NedtheNerd)
Disabling the windows firewall (Thanks Reallistic)
Entering the ip address as a manual connection (Thanks Reallistic)
Has solved the problem of the device being able to see the server and play a movie off of the server.
However it has spawned two new problems - 1) The movie seems to take a really long time to start (anywhere from 5 to 8 mins) before it begins to play (not a huge issue - but very perplexing). Problem #2 which is very concerning is that I have been unable to get two devices to play a movie at the same time. 1 Device will play a movie the second device will just sit and say talking to server but will never start while the other device is playing something. Any thoughts or ideas on how to solve these problems?