The things that strike me with hotspots, is how simple they are, and how difficult people make them. Most of the problems go away with reading more and preparation.
There are so many ways to break them or to fail how to get them to work first time that I will show you how simple it is to make them work.
I am a Raspberry Pi expert, and have built many repeaters, both Analogue and DMR and build all brands of code-plug.
You will need an image writer, one of many, such as Etcher, Win32, Raspberry image writer dependent on your favourite operating system. You will need a good quality known brand MicroSD card of at least 8 GB and no more than 16 GB. Any more than that you are wasting your money. Get a Raspberry Pi 3A+ or 3B+ and a good quality DC supply of 5V with at least 3A.
Obtain an enclosure with a fan, I repurposed a matchwood jewellery box painted black. Forget any Nextion screen or other mini device, as the goal is to hide this device out of sight, and to be transparent, so why waste money as I said before.
Get online and download the latest version of Pi-Star. There are enough links posted many times that nobody seems to read once they are there, so you should be able to find it. Version 4.1.5 is the source code.
Once downloaded into your machine, unzip it and using the SD card writer, write the image .img to the SD card. Once the card is written, Do NOT remove it from the computer. Instead go to your browser, and the Pi-Star page and run the WiFi builder page. If you can’t find it in the Pi-Star menu, there no hope for you. Follow the instructions for your own home WiFi or your MiFi if that’s your choice, and download the resultant file wpa_supplicant.conf to your computer first of all. Then copy and paste the same file to the SD card folder that should still be in your file manager. The next step may be controversial but I do it as standard. Click and open this folder on your desktop, then right click to create a new text file, that will in fact be empty, but name it ssh but remove the .txt that gets added by default in Windows and return. It should be a blank icon named ssh. Now you can eject the card, insert it into the waiting Raspberry Pi, and power it up.
For the next stage you will need some additional software on the PC. Firstly Angry IP scanner (my choice) and PutTy (also my choice).
Firstly run AngryIP scanner, where it will select your source network and search for open ports of all your connected devices hard wired or WiFi. By now or at least by 10 minutes of switching on the hotspot, it will have found your network, and this should manifest itself as PiStar.local on your network with an IP address.
My approach requires you to be a little adventurous first of all. Open the PutTy application and you will be presented with a box into which you type the IP address exactly as it was displayed on the IP scanner. By default you will see port 22 displayed in the attachment box. There are a number of boxes including Save, which you can do, so that you can return to the same screen another time, to highly this address from a list and select Load, but for this first time select Enter.
A terminal window will open now, where you will be prompted to input pi-star in lowercase, and the default password raspberry also in lowercase. What you type here will not be displayed on the screen so be careful, though you will be granted other opportunities if it fails.
If successful you will find yourself in the Pi-Star operating system in the root directory. We are going to update the Raspberry operating system first, something that Pi-Star cannot do on its own. Type exactly what follows, in lowercase. rpi-rw and type enter, then sudo apt update and type enter. Wait until all the screen operations are complete and you have a prompt available. If at any time a read-only prompt is returned to the screen, type rpi-rw again. Now type sudo apt upgrade and enter, and again wait until a prompt is returned to you.
Now we need to update the Pi-Star software. Again if you have a read-only prompt, type rpi-rw before proceeding to the next command which is sudo pistar-update and enter. Wait for the prompt, then type pistar-update and enter. If at any time you see that everything is reported as up-to-date, then type exit and enter and the terminal will close, maybe prompting you to confirm the action.
Then next steps require you to open your favourite internet browser and to type in the IP address as before, but this time you will be presented with a rudimentary Pi-Star dashboard as yet unpopulated with any callsign or data. What follows are the instructions for DMR only. If you are using other modes then I cannot help you. As DMR is the most complicated, I’m sticking with that.
You will largely be on your own as until you get it operational you will not get anything out of it.
You will need to make several decisions. Firstly you will have obtained a DMR ID of 7 digits as well as your own callsign, and decided on a frequency (or frequencies of you have a duplex hotspot) away from any other devices or other modes like the satellite band. For a duplex hotspot choose a frequency split similar to your repeater standard locally, 5, 7.6, 9 or 9.4 MHz. Note them down so that you can refer to them later. By now Pi-Star will have opened the configuration page.
Do not under any circumstances fill more than one paragraph at a time. Once one paragraph is completed then click on ‘apply’. To be frank any problem here on in, is going to be due to rushing ahead to try and do it all at once. It may be tedious but it will almost guarantee success if you apply only one parameter at a time, and wait for the screen to refresh before adding another.
Once you have reached the network paragraph do not select DMR-GATEWAY, but choose instead your nearest BrandMeister server. Do not worry about password at this time, as this will require further editing later. You will not connect directly if you are using a US server, you will need further editing later. For the ESSID in this paragraph select an additional two digits from the drop box alongside your ID. When eventually connected to the server, this 9 digit number will differentiate your hotspot from your personal ID. If you want another network, get it working on BrandMeister first, and change it later.
One important thing to examine on this page is the correct selection of the modem, that is the STM device sitting on top of the Raspberry Pi. There are multiple options, so be guided by the documentation that you received for your device. For Duplex hotspot selection, there is a choice of only two.
At this point you must leave the hotspot and go to BrandMeister.network on a new browser page. You will need to register for use on the menu bar, but it is free, and once registered and accepted (that may take up to 24-48 hours) you can select your profile and self care options.
In the USA it is mandatory to set a personal password for a hotspot, and it is within these settings you can choose it. It will also become mandatory elsewhere in due course elsewhere. This is for your own protection as some usurping of identities had taken place, and you wouldn’t want that, would you?
This password can now be used in the configuration below the selection of the master server in your Pi-Star settings. Click apply and you should see your hotspot appear in your personal account in the BrandMeister.network. Here you can edit what others see. There is one final setting that needs configuration to give you complete control over your hotspot in its local setting. By clicking on your profile on the BrandMeister.network, you select profile settings. You will see a small blue key on the right hand side that you must click. In the subsequent box that appears, create and name a new key. A box will open with textual content, and a QR code. Click on Copy, then with a text editor on your computer, create a new empty text file, and click paste, and this text information will be pasted into place. Save this file immediately to your computer, giving it a memorable name. Then open your configuration page in Pi-Star again, on the top line menu select Expert, and on the subsequent menu click on BM-API. A box will appear, into which you type control-v, which pastes the same text into place. Click apply, then click Admin on the main menu. You shall find yourself in the main menu where you can directly control the talk groups for DMR.
The next steps for setting DMR-Gateway are described in an article that can be found within these pages. They are not for the faint of heart, and as you have already discovered this is far from a plug’n play scenario.
Once you have the hotspot configured, the next stage is making your code plug do what you want with the dashboard. Again read some of the material in these pages.