@Sumty_AX73 You can't update with FW from a different FW region or from different HW version. That's pointed in the upgrade guide I posted. It's quite possible that your FW region is not an EU.

@Sumty_AX73 Here's how to determine HW version and FW region of the device. After finding FW region follow this guide to upgrade manually or via TP-Link Cloud service.

@Ninjaboy08 OK So it's an Archer C20 v2 EU FW (there's no newer version). What's your modem make and model ? Can you see the modem LAN port status where the C20 is connected ? Have you tried to use a...

@Ninjaboy08 Use a computer browser to access the router settings. If that's not your router interface a screenshot would be helpful to determine your device model and HW version - here's how can you...

@MrGuGuZai Use these wireless settings: Try to connect the modem to AX20 with another ethernet cable CAT 5E/6 or/and use a different modem LAN port. Use these DNS and Internet port settings if the...

@Micalen Try these wireless settings for the AX20 and test if you can connect to the printer: