How to make IPv6 work over Wi-Fi in Redmi Note 5?

Question

Android

Xiaomi Redmi Note 5 phone, I connect via 5G to a TP-Link Archer C6 router - IPv6 connection works on all devices (testing on test-ipv6.com ), except for this one. On Note 8 Pro, three IPs are displayed in the access point properties - local IPv4, local IPv6, external IPv6, and on Note 5 IPv6 only local, for some reason there is no external one:

and test-ipv6 shows that the address cannot be determined and IPv6 does not work .
What can be wrong? In both MIUI11/Android 9 phones, default hotspot settings.

Answer 1

Understood. This phone simply does not support DHCPv6 and therefore does not obtain an address from the server. Turned on SLAAC in the router and it worked.