Good sharing！

The modem has a security mechanism. If the router keeps working for a period of time, the modem will block clients to access the config page. Only a restart can let a client to login again.

Did you check the Network Adapters or Other devices on the Device Manager? Try another usb port or a different computer to avoid it is the computer issue.

Archer T9E is a network adapter. It has no firmware but driver. You can find the latest driver here: http://www.tp-link.com/en/download/Archer-T9E.html

It seems that the computer can't resolve this domin name. You may try a different device. The static IP is a good choice actually. The static IP is more stable to access to the web management page.

It seems the router won't add link aggregation function. The firmware hasn't been updated for about a year or so. You can send a feedback to TP-Link or return it to get a V2.