Country KH, Channel 149: A reproducible Wi-Fi interoperability failure, and the missing link between regulation and implementation

Abstract

Abstract An Ubuntu host on an ISP-supplied Huawei EchoLife HG8145V5 optical network terminal and wireless access point repeatedly disconnected from a 5 GHz network at approximately 65.5-second intervals. In the recorded failure condition, the access point was configured for Cambodia and advertised the IEEE 802.11 Country Information Element KH; its automatic channel-selection mode chose primary channel 149 at 5745 MHz, with an 80 MHz channel width. The Linux client associated successfully, then reported Channel is disabled, followed by a locally generated disconnect. The client was running Ubuntu 24.04.5 LTS, kernel 6.8.0-139-generic, with a Realtek RTL8821CE adapter using the in-kernel rtw88_8821ce driver. The retained log collection recorded 9,038 disconnect events over approximately one week. The observed loop was about 65.5 seconds long. The reported signal strength was approximately −48 to −50 dBm, with PHY rates around 390–433 Mbps and a noise floor near −90 dBm during the observed connection. Three controlled conditions were compared: Cambodia (KH) with channel 149, Cambodia with channel 36, and Vietnam (VN) with channel 149. The first condition repeatedly failed; the latter two remained stable. In a further test, two physical HG8145V5 units both selected channel 149 in automatic mode across the country-code settings tested. The current upstream Linux wireless-regdb Cambodia (KH) entry reviewed for this paper has no rule covering 5745 MHz; its highest listed 5 GHz range ends at 5710 MHz. The Android 17 AOSP snapshot is built from the same source. OpenWrt also consumes upstream wireless-regdb. A third-party extraction of a Ubiquiti U7 Pro Cambodia table shows a similar practical omission of channels 149–165. The author also found the HG8145V5 in the Telecommunication Regulator of Cambodia's public Type-Approved Equipment register. Separately, a 2022 TRC certificate for an Astronautics AFS6460 module lists WLAN transmit/receive operation in 5725–5850 MHz. These records provide regulatory context and identify specific documents for follow-up. The general Cambodian WLAN operating conditions applicable to the observed deployment still need to be established from an authoritative source. This investigation examines the technical mismatch between the tested access point's channel selection and the regulatory state applied by the Linux client, and identifies the technical and authoritative regulatory evidence needed to resolve it. The case illustrates a wider software-maintenance problem: national radio rules have to be translated into machine-readable data, reviewed, released, packaged, integrated into vendor products, and delivered to devices. Somewhere along that chain there has to be a Someone who connects the national rule to the code that acts on it.