Question about UniFi AP AC-LITE - 425959

Hello Digitec Community In our club building, two such access points have been in operation for about 6 months. However, they have been causing problems for 1-2 months. After about two weeks of operation, Internet access via the WLAN access point no longer works, but I am still connected to the network. This is via the guest and user WLAN. Internet access is always guaranteed via the cable connection. Restarting the devices always solves the problem. The power consumption of the access points is also easily covered. Power is supplied via PPPoE. Have you had similar experiences? What could be the cause? Is it possibly a defect/warranty case? Many thanks for your help!