OpenWrt has been rock solid stable for a few months. I've recently switched to a 1 Gbps WAN connection and for the last couple of days the system has been locking up and crashing. This seems to happen a few minutes after reboot.
The netdata application starts to have gaps in the CPU graphs:
Do you have a single (the onboard) ethernet for both WAN and LAN, or do you have a second device - i.e. some USB Ethernet device - if so, what make and model is it?
What are your temps when this is going on? Are you using a heatsink and fan? With those speeds you are probably hitting the thermal safety limit of 85C if you don't have good cooling. Probably overheating the usb controller or something too. Try running with the top open assuming you even have a case, that is.
You can also try packet steering (if you haven’t already), I’m not sure of the differences between it and irqbalance, but it serves the same purpose (network>interfaces>global network options).
Without either Packet Steering or irqbalance enabled, the download speed maxes out at around 520Mbps with SQM enabled, so they are definitely effective.
I think I have resolved the issue.
The syslog contained a lot of errors relating to the 'wan' connection, which is my previous PPPoE broadband. I had unplugged the cable, but left the configuration alone. Adblock was also running very slowly and may have been experiencing conflicts.
I've now completely deleted the PPPoE interface and luci is very responsive and appears to be stable with both irqbalance and packet steering enabled.
Good for you! For any future readers looking for Pi help, I run packet steering and irqbalance and have not had a problem with them on my Pi4B, however as always YMMV.
I personally found packet steering to slightly hinder performance on the Pi 4. irqbalance is good (and necessary!) but can be achieved through manual pinning of interrupts as well without risking them shifting around later.