I've been running 18.06.4 for quite a while and decided to migrate to the latest stable branch. I've read quite a lot about the wireless firmware changes (CT firmware among others) that took place and that seems to render this version less stable, based on general comments.
Unfortunately, it happened to me; quite unstable wireless performances reported by all family members after installing 19.07.2 - I had to go back to 18.06.4 because the helpdesk (e.g. ME) was overwhelmed by requests of malfunctioning devices... This was on a mixture of desktops, phones and tablets. About a dozen of different wireless peripherals are connected on my router, either on 2.4 GHz or 5 GHz.
I did a clean install, no settings preservation, basic reconfiguration and security settings. No applications were installed other than SQM for bufferbloat. Same wireless channels, same bandwidth and same security settings as before. No Routing/NAT/Software flow offloading, KRACK on, Disassociate On Low Acknowledgement on, but nothing really different from what was configured in 18.06.4.
I do not have a log because I rolled back to 18.06.4 quickly to preserve my sanity from incessant user's requests, but I could go back and try some things that are proven to work for your specific case.