@megabyt Check your TL-SG105 uplink cable. Such problems are caused often by poor cabling. Try with another cable if necessary - CAT 5E / 6.

@sunderan Use this video to setup your new router. If you still have problems watch this video to troubleshoot further.

@kimo555 Change DNS servers and check if that fixes your Internet status: Scroll down and set custom DNS servers:

@Bruzz Follow this guide for configuring the AP. Also check your cabling - connect the AP to a LAN port of your main router.

@Vicked That's not possible - these two routers have different menu, hardware and features. Sometimes even with the same router models this can't be done due to a new features or modifications have...

@ThisIsMe AX72 doesn't support bandwidth limiting for the guest network - see details about this feature here. This feature has been implemented to certain router models only.