In simple terms - you cannot have a normal internet acces without NAT ... You must disable NAT boost if you want to see if the problem persist. You find this settings under Advanced - System Tools -...

If you reported this problem , we asume YES... I reccomend to post it on new forums. This will be closed at the end of the month... https://community.tp-link.com/en/business/forum/3

Not loses connection. When it loses connection Hardware NAT crashes. This is a general problem/bug in software. All router with V4 (and now i heard that is possibly to be on V5 too) has this problem....

V4 has an unresolved bug with hardware NAT. I not reccomend it. If PPPoE connections drop accidentaly even for short period of time, hardware NAT crash and you will remain without internet...

There are hardware differences. At least for shure V4 does not have internal antenas. Only external...

Contact Tp-Link support from your country. Is the best way to report the problem and you know for shure that they will receive it...