The TL-WR340G is a 54Mbps (802.11g) router. No firmware will increase its speed to 300Mbps or add 5GHz support. If you need faster Wi-Fi, consider a hardware upgrade.
Official firmware files are provided by TP-Link based on regional hardware certifications. TP-Link Global Support tp-link wr340g v5 firmware download
They often pack malware inside fake firmware. The TL-WR340G is a 54Mbps (802
This FTP may be deprecated or read-only. You may find v4 or v6 firmware – do not assume they work for v5. tp-link wr340g v5 firmware download