sfx2000
22
The Nexus 5x and Galaxy Tab S3 - the wifi chips support HT40, however, it depends on the driver supplied by Android and/or the Vendor (LG/Samsung) to enable HT40 mode - two things that can impact - they might configure the WiFi chipset to 20MHz only, and they might set the 40MHz Intolerant Bit (this is how Apple devices can trigger an HT40 device to HT20 only)
WIth the Acer Laptop - they use many different vendors across their laptop line, so it would help to identify the Wireless Adapter (Vendor/Model - for example “Intel 3165”)
In any event, the adjacent networks in a busy area just might preclude wide channel operation - it’s conditional - consider it “up to 300Mbps”