How to create a ppp connection between a Psion PDA and a mint computer (Ubuntu)?

Question

linux

Dear colleagues, here we have been working on finishing linux on Psion 5 mx for a long time. Those. Linux itself was moved a long time ago, we just make it more or less usable.
mc on Psion 5 mx
Now the most important, last and urgent problem has arisen - this is to bring this PDA "to people", namely to the network. As I understand it, having only a COM port from the interfaces (in my case, only IRDA, but the meaning is the same), this can only be done via ppp
Now questions.
1. Where can I get good ppp documentation? Everything is either insanely outdated, or it is not clear how to cook. For example, here is the documentation on how to raise this ppp on Psion itself
linux-7110.sourceforge.net/howtos/series5mx_new/x4...
And I found good documentation on how to raise the server on the computerPPPoE server on Ubuntu 12.04 LTS . A number of questions immediately arise: is PPPoE compatible with that old ppp? Or do I need to dig in a different direction?
2. Whether there is a ready recipe of a raising of ppp through null modem? Style:

• Enter the XXX command on the server
  
• Enter the UUU command on the client
  
• see something
  
• ....???
  
• Profit!
  

And then you start reading some ancient mana, like this www.opennet.ru/docs/HOWTO-RU/PPP-HOWTO.html and it becomes not very clear what to do, who is to blame and how to run it on modern Linux.
3. Is it possible to force the DTR and RTS port signal lines to be at zero while ppp is running? This is due to the peculiarities of the operation of the infrared port on the PC side. Or is there a hardware problem to be solved?

Answer 1

PPPoE

And what in this dock does not suit?

Answer 2

https://www.howtoforge.com/linux_dialin_server
Maybe this will help