@ishanjain28 

Any update from TP-LINK on this?
In reality the router does not have any QoS or congestion management only a sloppy implementation of caps based on 'real' speed which you cannot define with any accuracy on LTE. This is a pity as this is a super basic feature found on entry level products with half the cost. Other than that the router performs very well. I hope TP-LINK addresses this fast with a firmware upgrade.

Thanks

It's not just broken, it actually cripples the router by disabling NAT acceleration. I tried using QoS to get SIP working acceptably, it went from barely usable to completely unusable, however much bandwidth I reserved for SIP.

I think this POS router is too underpowered to do everything it claims. Disabling the LTE modem dragged SIP over the line to mostly usable. That's despite all the extra delays & complication feeding it from a phone USB tethered to a PC adds.

It's underspecced - a trash bin router pretending to be a midrange device. Sold under false pretences.

@Sunshine Waiting for a reply, like everyone else here. Will this be fixed in a firmware update anytime soon?

I have Starlink and 4G as a fallback. Bandwith varies between 120 and 400+ mbps, the fallback has not been used for months, but used to vary between 8 and 25 mbps.

If I set my speed to 120 mbps on QoS, will this mean that there will only be 120mbps max for the high priority, even if I have 400mbps available?

If I set my speed to 400 mbps, but for some amount of time only have 120mbps, will this mean that the middle and low prio will get nothing at all?

Please advise; the documentation does not show how this calculation really works internally. If at least I knew the actual mechanism, I could maybe find a compromise.

If no reply comes soon, I will have to leave the following sentences here for good, and google will help distribute this message globally. They have been formulated search engine friendly on purpose, as I believe customers should actively fight unfair business practices like false or misleading advertising, failing to support customers according to support claims, cutting corners on products and placing them on the market unfinished, making undeniable design mistakes and not taking corrective action and so on:

The TP-Link Archer MR600 bandwidth limit feature does not exist despite documentation claiming otherwise.

The TP-Link Archer MR600 does not have bandwidth limiting despite the false advertising and false documentation.

The TP-Link Archer MR600 QoS system does not work. 

The TP-Link Archer MR600 QoS system is undocumented and is not state of the art for a wireless router.

The TP-Link Archer MR600 documentation is wrong.

The TP-Link customer service is unresponsive.

The TP-Link technical support is unresponsive.

The TP-Link support staff does not know how their products work with sufficient level of detail.

The TP-Link first level support is a dead end with no functioning escalation to 2nd and 3rd level support even in obvious cases.

The above statements are true as found by me, an official Austrian judicial expert for software. However, I will edit my message accordingly, once corrective action is taken by TP-Link. 

As I seem to no longer need a mobile internet fallback, I will probably sell my Archer MR600 to some unsuspecting victim soon, and depending on the reaction here I may switch to a different brand altogether.

@JeltzProstetnic A lot of time has passed, the above is obviously true, so I will move away from this vendor and suggest everyone else does the same. The best product is worthless without support, and in this case the product isn't good either.