Version: IR 1.7.1
Custom Modpack (with working IR 1.6.1): https://drive.google.com/open?id=1BPxiiGix1rZoxCrHa8zgzmtVT1ltjKu4

I'm reliably crashing the internal server whenever I hold shift and hover over an augment.
I swapped shift and ctrl so it might be ctrl - mouse over for you.

2019-11-18-3.log.gz

I would suggest switching to IR1.7.1 now that it is out. Also CTL is used as a secondary function for many mods. You may be having a conflict with mod config and controls due to your crouch button being changed

This bug is what's keeping me from upgrading to 1.7.1.

With 1.6.1 there are no problems. Nothing else changed.

@Yousei9 There's no error in that logs. Can you try to find the right log file?

Are those the reports you want?
crash-report.zip
logs.zip

Ok, this is fixed in the latest build which will be released tonight