Try to reset the network configuration back to the default DHCP settings and see what will happen.
Use the following commands on the host:
rm /etc/NetworkManager/system-connections/*
cp /usr/share/system-connections/* /etc/NetworkManager/system-connections/
nmcli con reload
How do I use those commands on the pi? Do I need to plug in a keyboard?
I managed to run this command to show available WiFi connections
It looks like many WiFi signals that are available in my area are not showing up. Including my own??
Move PI next to router and check
I’m right next to the router
It’s a mesh system with 5 access points my whole house is jam packed with WiFi lol
Few things that are different since my last router:
It’s now a mesh system
It’s now wpa2 instead of wpa1
And I cannot control the channel it’s on. It auto detects the channel for performance.
Why you cannot see your own WiFi - SSID ?
I don’t know? It’s not hidden in the router settings I can see and connect to the WiFi on my phone perfectly fine
Are you using MAC filtering?
Nope no filtering
Disable ==> enable WiFi on router and try connect/find WiFi on PI.
So when I run the nmcli command to list the WiFi in the area my WiFi is showing up.
It’s on channel 3 and security is WPA1 WPA2
When I type nmcli device wifi connect “decomesh” — ask
It prompts for password and then I get an error message
Set_key_mgmt invalid cipher group
Wl_set_key_mgmt failed
Connection activation failed the WiFi network could not be found
Yet when I do a scan for WiFi again it shows in the list perfectly fine.
I tried that command with and without quotes
I’ve decided to connect my pi directly to one of my decos now via Ethernet and it’s working but I would like to know what was wrong with the wifi.
As I am concerned that maybe this deco WiFi is not compatible with smart devices?
I plan to buy a few smart plugs switches valves etc I don’t want to find this issue again on all these devices after I buy them
Use wired connection (network cable).
And what do I do if I come across the same issue with all my esp32s and smart plugs?
I’d like to know what the issue is before I go investing in loads of smart devices
You ask the wireless access point manufacturer for support as it is unlikely to be a home assistant problem if this is the case.
It could be a chip-set compatibility issue, but these are not very common anymore these days. I don’t know what version of Pi you are running, but perhaps you could walk through the following checks/steps to troubleshoot. Afterwards you could increase settings again until it doesn’t work anymore 
:
Are you sure the WiFi uses WPA and not WPA2?
WPA2 is way more common and safer
Set your WiFi to support the lowest possible “speeds”, where possible make sure you support say 802.11G
Set your bandwidth to 20Mhz, changes are that it is set to 40mhz or more at the time.
If you changed the key for your WiFi, try setting the old key.
You know that key worked
If you dare, try setting your WiFi without a key to see if you can connect and thereby rule-out the chipset
Did you check/test connection to WiFi from esp32s and smart plugs?
I’ll return product back if it’s a problems.
Before check forum about TP-Link Deco Mesh WiFi System: TP-Link Deco Mesh WiFi
Also try use Fixed IP address . Just change ethernet to wifi and see if it’s will work for you.
No not yet as I havnt bought any esp32s yet.
Kasa smart plugs seem to work though.
Was just concerned that my new deco WiFi system was not compatible.
Will just use the wired connection for now and hope all is ok - thanks
