Mobile terminals at a certain site experience slow load when accessing a specific AP

AC: WX5840X version 5457; AP: WA6520. Primary and backup ACs, centralized forwarding.

In specific buildings, some apps on mobile devices load pages slowly when using wireless network, while other applications function normally.

 1、Created local forwarding to capture the interaction process of terminal accessing APP on AP uplink

It can be observed that accessing the URL xxx.xxx.com generated two DNS requests, with matching requests and responses, indicating normal DNS resolve

DNS Requesting to resolve the IPv4 address corresponding to the domain xxx.xxx.com (A represents IPv4)

DNS Requesting to resolve the IPv6 address corresponding to the domain xxx.xxx.com (AAAA represents IPv6)

Packet capture shows that the terminal uses dual stack when interacting with the website. It first initiates an IPV6 interaction but keeps retransmitting after sending SYN. After multiple retransmission failures, it uses IPV4 for website interaction, resulting in slow loading but ultimately displaying the page normally.

2、Subsequently, a pure IPV6 website access test was conducted. It was found that the resolution succeeded, but the page failed to load, and the domain could not be pinged. However, pinging the gateway worked normally.

1. 3. On-site review of the network revealed an additional gateway between the gateway and the egress point. Ping tests failed, and it was found that the routing device had not enabled the IPv6 address for this building.

Enable the IPv6 address of the building on the routing device. After modification, the issue was resolved.