If you are looking for the actual technical resources to update your device, you can find them here: Official Tenda Download Center: Tenda Support - D305 Update Steps:
Rohan hesitated. This was the digital equivalent of eating a mushroom from a dark forest. It could fix everything. Or it could brick the router into a useless paperweight. tenda d305 firmware update link
No. Tenda often releases region-specific firmware (US, EU, AU, CN). Using the wrong one might disable certain DSL frequencies. Always select your country or use the "Global" version if available. If you are looking for the actual technical