Is there any reason why, according to the title, you think it no longer connects to WiFi?
Surely the WiFi-chip is working, as it can still operate as an access point when in configuration mode. When in doubt if it connects as a WiFi client, then that might be easily validated in some web interface of your WiFi access point, or by using some ARP command within the same network? (I don’t know if the TTIG would respond to a ping.)
Aside, just in case it helps, it seems that the last_seen in https://thethingsnetwork.org/gateway-data/gateway/eui-58a0cbfffe800d06 (and https://www.thethingsnetwork.org/gateway-data/user/paul_b) confirms it does not connect to TTN, even if it has connected to WiFi. But I guess that just confirms what you see in TTN Console:
{
"id": "eui-58a0cbfffe800d06",
"description": "AG Office GW",
"owner": "paul_b",
"owners": [
"paul_b"
],
"attributes": {
"brand": "The Things Industries",
"frequency_plan": "EU_863_870",
"model": "The Things Indoor Gateway",
"placement": "indoor"
},
"last_seen": "2019-12-22T17:18:29Z"
}
Similar details for http://noc.thethingsnetwork.org:8085/api/v2/gateways/eui-58a0cbfffe800d06 (beware, that’s an HTTP URL; right-clicking and some “open in new incognito window” might help if your browser tries HTTPS instead):
{
"timestamp": "2019-12-22T17:18:29.334663621Z",
"uplink": "1025",
"downlink": "460",
"location": {},
"frequency_plan": "EU_863_870",
"gps": {},
"time": "1577035109334663621",
"rx_ok": 1025,
"tx_in": 460
}
And another aside: if you feel like some soldering then you can get debug output, either using the USB connector or some UART wiring on the PCB, obviously voiding the warranty…