5GHz WiFI speed much slower than on 2.4GHz on my Macbook air 2017 I just setup my new Xiaomi WiFi MiRouter 4A gigabit edition router but my Macbook has only 3MBs speed of uploading while on 2.4GHz speed is 60MBs. Also on iphone and other devices is almost 200Mbs speed. I deleted my antivirus app and vpn but still didn't help. I don't know what to do.
Found solution. Issue was in the settings of bandwidth, changed from 20Mhz to 80 Mhz.