I'd never tried this mode in its heydey in the 1990s, so up to now my only foray into Amateur Packet-based communications has been APRS. But then in 2017 Jack G8HIK prompted a few local stations to dust off their old TNCs to give it another go, and I joined in, using the UZ7HO programs Soundmodem and EasyTerm running on an old WindowsXP "scraptop".
Then a couple of weeks later I updated the DireWolf sound-modem on my Raspberry Pi to version 1.4 which supports "Connected" mode packets, and had a go with this too.
The Pi doesn't have a sound-card input, but this is easily remedied by the addition of a USB-audio dongle. And the radio's PTT is controlled simply from a transistor wired to one of the Pi's GPIO lines. The advantage of this setup is that while this Pi-TNC is set up next to the radio, I can run the Terminal program on my laptop anywhere in the house, connecting back to the Pi's port :8000 via WiFi.
I've been using the AGW Terminal program as my user interface, as well as a TightVNC link to the Pi's desktop, to keep tabs on the live traffic on the TNC.
Next I wrote a batch-file (which runs from a Desktop Shortcut) to connect to the Pi3 using SSH and then start up DireWolf, so that its terminal output is shown in a window on my laptop's Desktop. This also sends the PC's clock-time to the Pi (which in the "WiFi direct" configuration isn't connected to the internet, so it has no way of synchronising itself).
And now I've set up my old Pi2B with the same system too. This connects to my main WiFi router, so it allows me to operate the TNC from anywhere in the house.
And I'm using the UZ7HO EasyTerm program with this - it works better than AGWTerm, as it automatically re-synchronises with the PiTNC if there's an interruption in the WiFi link. Plus it has a built-in Mailbox.
If you'd like to join in, we're on 144.950: look out for the beacons from G8HIK or G4JLG, and leave a message in their Mailbox.