@UniKL_MIIT 

IPsec work pretty good for me but if you use OpenVPN or SSL VPN then IPsec is destroied.

So my advice is to remove all settings from SSL VPN reboot router, then You can use OpenVPN but only with TCP, Not UDP that is deafult.

OpenVPN is also paintfully slow, for me about 20-30 Mbps MAX.

to be honest, we have been very patient in this case, such a serious error is very embarrassing for tp-link, it also doesn't seem like they have competent people to fix the problem.

because the router has a different working mechanism that makes it difficult LoL  Or what @Fae 

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