2017-models TP-Link WiFi repeaters (including TL-WA855RE V1, TL-WA850RE V2, RE650 V1, RE500 V1, and RE450 V1) all hardcode au.pool.ntp.org and nz.pool.ntp.org worldwide, and sends one NTP request to whichever is the first IP address returned by either DNS requests once every 5 seconds. time.nist.gov and three others are also in the hardcoded list.
TP-Link is using NTP as an aggressive internet connectivity check, and squanders 715 MB/month on this “feature” for each of their customers. It can’t be configured or disabled in TP-Link’s firmware.
I think you may want to discuss more than just vanity pool names with TP-Link….