IPhone 6 resetting cable modem when connected to wifi

My cable modem, which provides wifi and Ethernet connections, completely resets whenever I use wifi on my iPhone 6. The iPhone seems to connect fine.

Other facts:

-several wifi devices including iPads work flawlessly

-Ethernet connected devices also lose connectivity when the iPhone is used for anything significant in wifi

-The modem resets completely, all lights off for upwards of a few minutes.

-turning off wifi for a night on the iPhone and all issues go away until the wifi returns and the phone is used.

-phone seemed issue free before latest update

-Waiting on replacement modem.

-have tried both the 2.4GHz wifi network and 5GHz wifi.

After reading other questions on the forum this seems to be a recurring issue.

Thanks.