Man, I feel your pain on that setup trouble! We've all been there after a long break. Those technical hiccups can really mess with your confidence right before showtime.
That amplifier connection mixup is classic - I've done the same thing when rushing through setup. And that
speaker cable not fully connected? Brutal! Nothing worse than starting your show and realizing you're only running mono instead of stereo. I bet the sound suddenly doubled in awesomeness when you fixed it mid-show!
The WiFi issue with OpenKJ is definitely frustrating. You're right about that being a design flaw compared to Karma's forced login. OpenKJ should really have some kind of connection status indicator that's impossible to miss. Maybe worth posting that feedback on their forums?
Glad to hear it went well otherwise though! Getting back into live shows after COVID is an adjustment for all of us. Were you running your usual audio chain otherwise? Any new gear in the setup that might have contributed to the confusion? Always curious what fellow audio folks are using these days.
Hope your next gig goes smoother on the technical side!