What firmware are you using? and what is the issue for your modem exactly? You may give the details to tplink tech support ( support.sa@tp-link.com) to get help.

The log shows that the device connected to LAN 4 port is disconnecting and re-connecting. Probably your X-BOX is turning off and on the Ethernet connection in Standby mode.

What's the model number of our smart plug? and which app are you mentioning?

What's the issue with your TL-PA9020P? Is there any error message when the second one fails? I think you can tell tplink the details by sending them emails to get help.

Also cannot find the old firmware. I think it is removed by TP-Link. For your issue, you may contact TP-Link email support to get help.

Theoretically, the range extender should be cable to connect to wifi and give internet via Ethernet cable. But there are some limitation: 1. the wifi from your Dongle should be using normal wireless...