Question How can I troubleshoot home wifi randomly dropping to lower Mbps ?

[surfer949]

My in laws have a Linksys WRT 1200 AC routers connected to a Comcast modem with a 80 Mbps subscription. But at random it drops to 30 to 40 Mbps on home 5GHz wifi network. Even if I'm standing in front of the router! What app/tools can I use to troubleshoot this? Pings at 17 to 25 ml seconds use Meteor apps on mobile device. Thx.
And when I was testing bandwidth usage was limited to two to 3 device at home.

 

[rgd1101]

try ethernet to modem to make sure is the Comcast issue?

 

[surfer949]

try ethernet to modem to make sure is the Comcast issue?

Oh good one. Ok I'll test that thank you!