Problem occurs on any router from the AX series.

You can't set guest bandwidth limits or for a specific device, these should not as of yet be used on any more complex network (such as a business) until TP-Link (an awesome company) resolves these issues.

The idea is as follows, if you want to limit the bandwitdh for your guest wireless network for instance or a specific router, you will be unable.

Currently you can only set QOS control which enables you to set the limit on your WHOLE router/network which is useless if you have for instance a company computer that requires 100/100 mbps and you to limit the network for 2/2mbps for guests.  Someone might say there is packet prioritizing, this feature is mostly useless and will not provide true bandwidth control even if it worked (but it doesnt).

Summary -

The routers dont have bandwidth control (they used to but they have removed it), QOS doesn't work and should be reverted. This issue should take priority over all others as many, many customers have this need, even in a simple home setting when you don't want your network lagging because a child is live-streaming a game or watching netflix.