I’m having an issue where devices on my network won’t be able to get an IP from the DHCP server on my modem.

It’s random. Could be my iMac, my HomePod, Wemo or Leviton light switches, MacBook Pro. 
Restarting the device doesn’t help. Restarting the Hitron router always does fix the issue. 

I have other access points in the house, so not all Wi-Fi devices are connected to it, and a decent amount are over Ethernet. Everything is able to connect to Wi-Fi not an issue, it’s just not able to grab an IP.

I have done a factory reset on the modem as well.

I’m hitting approx 22 items (at least) on the network, is there a limit?