Ugh, this is just a sea of settings, so it is hard to know what has been causing access losses, but something I did seems to have worked:

1. The apple devices no longer get disconnect messages. I'm going to start turning things back on and see what is broken. But I turned basically all the fancy stuff off. Like Advanced features and then all the various network minimums
2. However, the LG C6 still will not connect. I tried what was recommended for it. Turn off Smart Start. Turn off time connection. But it still will not connect. Also split the network into a 2G and 5G on the theory it's 5G wasn't working

So here is what I've done and here is what is broken and a list of things

1. Tried to make the Unifi Cloud Key work again. I have the gen 1 and it kept on crashing. It would be nice to have it running again. Turns out there is a reset button as you really shouldn't just yank it out like I do. You find a paper clip on Gen 1 versions, push it for 10 seconds and then you will see a blue and white flashing sequence. You then need to find it with a lan scan or look at magic address 192.168.1.30.  to find the recovery.page and rebuild it. You then find the right file and force a download.
2. I really should get an Unifi USG Pro 4 and the new Unifi Cloud Key Gen 2. Then I can move my current Edge to another site (more gifts for relatives) and manage them remotely which would be really nice.
3. It was constantly rebooting and hanging and in reading the guides. Basically, don't just pull it out. Reset it from the web user interface, or by hitting the reset button. It has a micro SD in it with the configuration files, so make sure that thing works. The biggest reasons for a problems are power failures so the MongoDB gets corrupted or a full SD or a bad SD.
4. I don't get any alerts because the mail from the Unifi Controller doesn't work. I'm tearing my hair out on this one. But I set it with an app specific password. I tried using their cloud mail. The errors are unknown error and invalid email address. I checked my unifi cloud account and that seems fine.

Then there is Mike's guide to setting this up, so I tried a few things:

1. Change the Access point settings from Auto to Medium. It looks like Auto means high, so I'm seeing devices connecting all over the house.
2. I turned back on advanced features but turned off but I left the AI Scan on, this seems to be assigning power to different APs and moving them around.
3. I did turn the power down to Medium as several guides said that Auto just meant High. I am seeing devices connect mysteriously all the way across the house when there is an AP in the next room so maybe that helps.
4. Most of the pro's do manual band allocation. I'll let the AI work for a while.
5. I made sure I don't have VHT 160Mhz turned on, it reduces the power and non of my clients can use it yet anyway. The reason for this is that you get 1 watt of transmit in the UNII-1 (channel 36+) and UNII-3 (channel 149+), but in the UNII-2 new channels, you are only allowed 250mW if there are no airport radars detected. It uses DFS to detect this.
6. I turned back on Advanced Features which enables airtime fairness, bandsteering and minimum RSSI. We will see if this is the stability problem.
7. I did turn off UAPSD and fast roaming because that guide says that fast roaming is buggy and you do get drop outs for some clients.
8. I turned back on multi-cast enhancement (IGMPv3)
9. I also have intrusion prevention turned on, but really this requires the USG so it's not the stability problem.