Hi scottd112467,
Here are some tips for the Scarlett Solo:
1. Turn off Direct Monitor. Direct monitoring can make it hard to know what volume others hear you at.
2. Make sure the Inst button is enabled when connecting a guitar cable to Input 2.
3. Check that the Input 2 light is not red when you are playing guitar. Red indicates that the input is too loud (try turning down the Gain 2 knob).
In jammr's sound settings (File | Settings on Windows and jammr | Preferences on Mac):
1. Enable the “Play back my audio” checkbox.
2. Set Sample Rate to 44100 or 48000 Hz.
3. Set Latency to around 10 milliseconds. You can try lowering it to around 5 milliseconds once sound is working.
Note that jammr's sound settings cannot be changed while you are connected to a jam session. File | Disconnect will leave the jam session.
After changing jammr's sound settings, connect to a jam session to check your audio.
The “Send” button in the bottom-right corner of the jammr window controls whether other users can hear you. You can disable it while experimenting with the sound settings and enable it again once you're ready to participate in the jam.
If this does not solve the issue, please go to Help | Show log and copy-paste the technical information that gets displayed and post it here so I can take a look.
There is a step-by-step audio setup guide here:
https://forum.jammr.net/topic/1987/