Xiaomi unveiled the Redmi Note 9 series in India earlier this year in March, with the launch of the Redmi Note 9 Pro and Redmi Note 9 Pro Max. Almost a month after its India debut, the series was launched globally but, with a few changes. The Redmi Note 9 Pro Max was launched as the Redmi Note 9 Pro, the Indian Redmi Note 9 Pro was launched as Redmi Note 9S, and the company added a new Redmi Note 9 into the mix.

As with previous devices in the Redmi Note lineup, Xiaomi managed to pack in some impressive hardware into the Redmi Note 9 series while still keeping the price quite low. The devices featured Qualcomm's Snapdragon 720G and MediaTek's Helio G85 SoCs, up to 8GB of LPDDR4x RAM, up to 128GB of UFS 2.1 storage, and massive 5,020mAh batteries with up to 33W fast charging support. On paper, the devices seemed quite compelling, and in our review of the Redmi Note 9 Pro, we found the device to be an excellent choice in the price segment. However, we've now learned about a concerning issue with the Redmi Note 9 Pro/9S which is bound to take a massive hit on its reliability.

According to recent posts on the Mi Community forums, XDA and Reddit, a few Redmi Note 9 Pro/9S owners are facing issues with WiFi connectivity on the device. Users claim that the device drops WiFi connections when the screen is turned off and the device goes into standby mode. While the device shows that it's connected to WiFi when you turn the screen on after a while, it doesn't seem to work and you have to manually turn WiFi off and on again in order to get it working.

While we aren't exactly sure what causes the WiFi issue on the Redmi Note 9 Pro/9S, some users suggest that it could be hardware-related, specifically due to a bug in the hardware-based cryptographic acceleration engine that handles WiFi encryption processing. Tushar from our team tried to recreate the issue on his Redmi Note 9 Pro (firmware version 11.0.7) and he noted that the WiFi speed dropped drastically when the screen was locked. However, in his case, the speed was restored as soon as the screen was turned on. He also noted that while Play Store downloads didn't continue after the screen was turned on, downloads on Google Chrome did.

Some users on Reddit claim that Xiaomi has acknowledged the issue and is currently working on a fix, however, we haven't seen any official comment from the company. We will update this post as and when Xiaomi releases a statement regarding the issue.

Source: XDA Forums, Mi Community, Reddit (1,2)