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 
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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
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Set your bandwidth to 20Mhz, changes are that it is set to 40mhz or more at the time.
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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