no IPV4 address via Motorola modem

hello,

i recently switched to a 3rd party non-xfinity modem and while the device was successfully activated, it is not pulling an IPV4 lease, only IPV6. this has led to a ton of issues on my network, most importantly causing my router to lose connection every few hours. I've read on some posts in this forum that there are some wonderful people here that can help me, as customer service has been a nightmare to try to work with.