Thank you. I did exactly those step prior your suggestion and downgrade; however I just did the ver. 386_49599 as you mention and Bang! all my IoT are back and fast responding! (I'm shock) now I'm 100% that the 388.xxxx have an issue or bug they haven't figure out. may be because they have focus on Wi-Fi 6 feature or improving 5g, nevertheless no doubt it's on the firmware . Not everyone use lots of device on 2.4 need it like me, but again not a lot of option when it come of IoT, except the long waiting "Matter" (Thread .. didn't make it ) , still love having lots of device in my house instead flipping switchesUse this to start:
If it doesn't help:
2.4GHz:
- Set fixed Control Channel, not Auto
- Set Channel Bandwidth to 20MHz
- Disable TX Bursting
- Disable WMM APSD
- Set Modulation Scheme to 802.11n
- Disable Airtime Fairness
- Disable MU-MIMO
- Disable all Beamforming
If still issues:
- Set Group Key Rotation Interval to 7200 or even 86400
- Disable DNS-over-TLS if enabled, some IoTs don't like it
If still issues:
- Try different firmware release, 386_49599 is good