Hi. Any luck with this? If not a few other thoughts;
Before digging into my questions below, if you can, I’d do a full power cycle of the panel for good measure.
Was this working before, on the same ssid with the same password? Any network changes? What hardware are you using for your wireless (just curious)
If you go into settings, installation, devices, wifi devices, wifi - do you see a list of available wifi networks that are broadcasting? Is your target network listed?
If you connect a test laptop to that same ssid with the same password, can you browse the internet?
Just as a test, you could try turning off band steering and set it to 2.4 only.
When the panel goes into this odd state (connected but no internet), does the speed, connection type and IP address of the panel make sense, or is it reverting to an auto configuration IP address, etc? (169.254.x.x) (under settings, advanced settings, about, wifi Information)
Any chance of a firewall rule blocking outbound access somewhere?
(This is all assuming the ‘briefly connected and then connection stops’ scenario is still occurring. ). Hope this may help.