I managed to get the USB wireless LAN adapter TP-Link Archer T3U AC1300 working on a Thinkpad X1 Carbon 2015 (Fedora release 29 (Twenty Nine), linux 5.3.6-100.fc29.x86_64), so I’m documenting the procedure.

# The official website didn't distribute drivers, so I used rtl88x2bu
git clone https://github.com/cilynx/rtl88x2bu
cd rtl88x2bu/
git rev-parse HEAD # 962cd6b1660d3dae996f0bde545f641372c28e12
VER=$(sed -n 's/\PACKAGE_VERSION="\(.*\)"/\1/p' dkms.conf)
sudo rsync -rvhP ./ /usr/src/rtl88x2bu-${VER}
# Move to /usr/src/<module_name>_<module_version> and manage with dkms
sudo dkms add -m rtl88x2bu -v ${VER}
sudo dkms build -m rtl88x2bu -v ${VER}
sudo dkms install -m rtl88x2bu -v ${VER}
sudo dkms status
sudo modprobe 88x2bu

When connecting two types of adapters (onboard adapter and TP-Link adapter) to the same network, priority is determined by metric. Looking at the metric values, the onboard adapter was prioritized (smaller value), so I swapped them.

ip route
sudo nmcli con mod <connection name> ipv4.route-metric 599
sudo systemctl restart NetworkManager

Note: No particular issues after updating to Fedora 30 and 31.

sudo dkms status
# rtl88x2bu, 5.6.1, 5.3.6-100.fc29.x86_64, x86_64: installed
# rtl88x2bu, 5.6.1, 5.3.8-200.fc30.x86_64, x86_64: installed
# rtl88x2bu, 5.6.1, 5.3.8-300.fc31.x86_64, x86_64: installed