Here are the settings that resolved my issues with iOT devices and the RT-AX86U

[iFrogMac]

Thanks for sharing images of the settings you've tried. I've been having issues with some WiZ bulbs recently (model 23007, specifically) that can't maintain a wireless connection on an AX58U. I also have a Nest Hub that has always had issues with this router, but applying ASUS's recommended IoT compatibility changes seems to have resolved that device's issues.

I'm going to try some of the settings you suggested and hope to see some improvement with these bulbs. I'll report back with any results.

Also, in my case I'm only using this router as an access point, so have no reason to suspect DHCP issues. Though, I have tried setting static IP's to the bulbs with no improvements.

I've only had one issue with my current settings, one bulb dropped, but a power cycle brought it right back, and it's been fine since. one thing I did when this happened was unplugging the Google Nest Audio speaker in the living room, once I reconnected it and the Nest Audio rebooted and connected, the bulb dropped so it's possible the Nest audio did something on the network. Nothing else dropped except the one bulb.

Router has been up a full 2 weeks now and a little bit extra at this point with no further problems to report.

 

[kmartshopper]

I've only had one issue with my current settings, one bulb dropped, but a power cycle brought it right back, and it's been fine since. one thing I did when this happened was unplugging the Google Nest Audio speaker in the living room, once I reconnected it and the Nest Audio rebooted and connected, the bulb dropped so it's possible the Nest audio did something on the network. Nothing else dropped except the one bulb.

Router has been up a full 2 weeks now and a little bit extra at this point with no further problems to report.

So far my network is looking good after limiting the mode to Wireless-N in addition to all your other settings. I've noticed some persistent logged output has ceased, which may be related to the connection issues I was seeing:

eth5: Deauth_ind 84:B8:B8:58:F2:D0, status: 0, reason: Deauthenticated because sending station is leaving (or has left) IBSS or ESS (3), rssi:0

This isn't an ideal solution, so I might tinker with settings some more. If the log output above indicates an issue, that might help troubleshoot this faster than waiting for one of the bulbs to go offline.

 

[iFrogMac]

So far my network is looking good after limiting the mode to Wireless-N in addition to all your other settings. I've noticed some persistent logged output has ceased, which may be related to the connection issues I was seeing:

eth5: Deauth_ind 84:B8:B8:58:F2:D0, status: 0, reason: Deauthenticated because sending station is leaving (or has left) IBSS or ESS (3), rssi:0

This isn't an ideal solution, so I might tinker with settings some more. If the log output above indicates an issue, that might help troubleshoot this faster than waiting for one of the bulbs to go offline.

I think I posted my updated settings, I run 2.4 in auto mode without issues. The only exception is WiFi 6 is disabled for 2.4Ghz and enabled for 5Ghz only.

 

[kmartshopper]

My bulbs started going offline with 2.4 in auto

But, it's a start! I'm not happy having to mess with Wifi to accommodate some IoT devices, but would prefer not to run a second access point just for these devices (which I have ready just in case this all fails).

 

[iFrogMac]

My bulbs started going offline with 2.4 in auto

But, it's a start! I'm not happy having to mess with Wifi to accommodate some IoT devices, but would prefer not to run a second access point just for these devices (which I have ready just in case this all fails).

First I tried the RT-AX82U which I believe has the same hardware as your 58U. I couldn't get the issues resolved the 82U. So, returned it to Amazon and got the 86U. The different hardware / firmware probably comes into play with this issue.

 

[kmartshopper]

Sadly it's way past the return window for my AX58U. On the plus side, it's been working pretty well this afternoon. Occasionally Hue devices appear to cycle their connection, but I think that's normal.

I ended up leaving Wireless Mode on 'Auto,' and set a fixed Control Channel to a minimally congested channel. Of course, the connectivity issues could return in the next day or so, so I'll keep an eye on things and update tomorrow.

 

[iFrogMac]

Sadly it's way past the return window for my AX58U. On the plus side, it's been working pretty well this afternoon. Occasionally Hue devices appear to cycle their connection, but I think that's normal.

I ended up leaving Wireless Mode on 'Auto,' and set a fixed Control Channel to a minimally congested channel. Of course, the connectivity issues could return in the next day or so, so I'll keep an eye on things and update tomorrow.

Also make sure your firmware is up to date, that's another thing that helped. The latest firmware is much better. There was only really one firmware that was pretty bad with this issue for the RT-AX86U, and Asus updated it pretty fast. So, make sure you router is also up to date.
In the event you continue to have issues you can't resolve, try a TP-Link router, they seem to work well for smart Homes and don't cost an arm and a leg. The Archer AX4400 is the TP-Link I have, and it's a good solid router to fall back to when the Asus won't function as needed.

 

[kmartshopper]

Well, it didn't quite work. The lights seemed more stable the first few hours but several have become unresponsive. The router reports them all as connected in the logs, but they won't respond to a ping.

I am already using the latest firmware, but thanks for the suggestion. It seems like somewhat recently the lights started having these issues, and it's only affecting one model number, while one identical bulb with different model # works perfectly. For now I'll run them off my old Wireless-N router and hopefully can get some stability out of them.

I've attached one of the signal graphs captured from Home Assistant. It just starts puttering out sometimes, as if the Wifi is having issues, but I can't really be sure.

 

[iFrogMac]

Well, it didn't quite work. The lights seemed more stable the first few hours but several have become unresponsive. The router reports them all as connected in the logs, but they won't respond to a ping.

I am already using the latest firmware, but thanks for the suggestion. It seems like somewhat recently the lights started having these issues, and it's only affecting one model number, while one identical bulb with different model # works perfectly. For now I'll run them off my old Wireless-N router and hopefully can get some stability out of them.

I've attached one of the signal graphs captured from Home Assistant. It just starts puttering out sometimes, as if the Wifi is having issues, but I can't really be sure.

The Lights that really had issues for me were the MERKURY bulbs from Walmart. They use the Geeni, or Smart Life app as they are usually just rebranded Tuya Smart lights. The Wiz bulbs have generally been much stabler. I have mostly Philips wiz A21, and A19 bulbs with one Wiz branded A19 bulb. The MERKURY lights are decent, they just have a locked white mode to soft white and the colors are bright, but don't get as bright as the Wiz. They also have Alexa Scene integration while the MERKURY do not.

I also checked on the Wiz support site, and they say their devices use b, or g networks, so I wonder if that's why legacy mode might help you with the Asus. It forces the network to run at g speeds, and you can disable b/g protection to get full speed. Also, setting security to WPA2+AES will also prevent b devices from connecting. Depending on what devices you have on the 2.4Ghz network besides the bulbs, you won't notice any network performance differences unless you use devices that can go faster on 2.4Ghz. What I suggest is putting anything on 5Ghz that can handle it, and saving the 2.4 network for iOT devices. That was my initial setup, but like I said, after the latest firmware update, doing a hard reset, and changing the settings listed in this thread, things have been stable. Maybe try a reset, if you haven't already, after updating to the latest firmware and see if maybe you have some bad settings in memory.

By the way, the remaining MERKURY bulbs I have in use, I removed from the Geeni App and have paired them with Tuya Smart Life, and they've also now been stable. The only two lights left in Geeni, are my LED strip lights, and they also seem stable now.
Hope this helps

 

[kmartshopper]

Well, I ended up connecting the problem lights to my old AC access point, and 24hrs later not a single disconnect has occurred. I somehow had managed to cause other issues with my AX58U where 5Ghz devices somehow weren't discoverable on the network, so ended up factory resetting that as well.

But, thanks for all your help!