Since 2018 my C7 AC 1750 has been working flawlessly. For the last week however, it drops my 2.4 GHz connection every few days. The 5 GHz connection works fine. Using the 2.4 GHz wireless connection are one Toshiba laptop, two Alexa speakers, and two cellphones. The problem seems to occur when one of the cellphones is using WhatsApp. If I reboot the router, then the 2.4 GHz connection is re-established and the Alexa and the cellphones can use it.
Where can I look for the problem?