GL-AX1800 (as repeater) resolve "captive.apple.com" fail:

I don't understand this failure message:
The GL-AX1800 Flit is setup as a wireless repeater.
The main router, also running openwrt, has address 10.0.0.1
In the GL-AX1800's logread, I keep on seeing the following error messages, why am I seeing this? And what is captive.apple.com. We have no Apple product in the house by the way. Every machine is either PC, or Linux running on Raspberry pi.

Tue Jun 24 19:50:02 2025 daemon.err gl-repeater[2062]: (repeater-portal.lua:335) detect portal fail: resolve "captive.apple.com" fail: recv from "10.0.0.1:53" fail: timeout
Tue Jun 24 19:50:02 2025 daemon.err gl-repeater[2062]: (repeater-portal.lua:335) detect portal fail: resolve "captive dot apple dot com" fail: recv from "10.0.0.1:53" fail: timeout
Tue Jun 24 19:50:32 2025 daemon.err gl-repeater[2062]: (repeater-portal.lua:335) detect portal fail: resolve "captive dot apple dot com" fail: recv from "10.0.0.1:53" fail: timeout
Tue Jun 24 19:50:32 2025 daemon.err gl-repeater[2062]: (repeater-portal.lua:335) detect portal fail: resolve "captive dot apple dot com" fail: recv from "10.0.0.1:53" fail: timeout
Tue Jun 24 19:51:52 2025 daemon.err gl-repeater[2062]: (repeater-portal.lua:335) detect portal fail: resolve "captive dot apple dot com" fail: recv from "10.0.0.1:53" fail: timeout

Hello,

When the repeater is connected, this process is used by the router to check whether the primary WiFi exists the captive portal page, this is normal behavior.

If the primary WiFi you are connected to does not exist captive portal, the repeater connection is normal, and the Internet accessing normally, it does not pay attention to this log information and can be ignored.