Constant DHCPOFFER/DHCPDISCOVER for modem/router device

For our AT&T fiber, we are required to use a supplied modem/router (ARRIS BGW210-700) which does not allow setting DNS servers manually. I was happy to find out that I could get around this by moving DHCP services to the PiHole. Perfect. I disabled the DHCP on the ARRIS and enabled the service on the PiHole. And now every device is using the PiHole for DNS with an upstream DNS from Cloudflare instead of AT&T's slow DNS.
Everything is working fine.
When I look at the pihole-log though, I see pages and pages of this:

Dec 30 05:47:09 dnsmasq-dhcp[598]: DHCPOFFER(eth0) 192.168.1.102 88:96:4e:e7:ad:22
Dec 30 05:47:10 dnsmasq-dhcp[598]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22
Dec 30 05:47:10 dnsmasq-dhcp[598]: DHCPOFFER(eth0) 192.168.1.102 88:96:4e:e7:ad:22
Dec 30 05:47:10 dnsmasq-dhcp[598]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22

Always the same IP. Always the same MAC address. Always between 1 and 3 seconds apart.
I never get anything other than OFFER and DISCOVER, so I think my issue is different from DHCP offers are not accepted.

I did some digging about MAC addresses and found that the MAC address can tell you about the manufacturer of the device. I discovered that 88:96:4e corresponds to ARRIS. I checked the modem/router on it's status page and found that the 2.4Ghz network MAC address is 88:96:4e:e7:ad:20, the Guest network MAC address is 88:96:4e:e7:ad:21, and the 5Ghz network MAC address is 88:96:4e:e7:ad:23.
So this seems pretty conclusive that the device that will not accept it's IP address is part of the modem/router, but I'm not sure what it is or how to get it to accept it or stop requesting it. I expect that the advice I'll get is to take this to the dnsmasq mailing list so I'll do that too, but if anyone has any thoughts on what it might be, I'd appreciate it. Thanks.

Expected Behaviour:

Normal log output without spam of DHCPOFFER and DHCPDISCOVER.

Actual Behaviour:

Log output contains spam of DHCPOFFER and DHCPDISCOVER.

Debug Token:

fpvx6do4m9

Okay. I asked for help from the dnsmasq mailing list and was told I could try using dhcp-mac and dhcp-ignore to just ignore the requests that are causing the log output.
But those CLI tools don't seem to be exposed. How can I do the equivalent of running these commands through the dnsmasq installation in PiHole?

My netatmo weather station did that too, changed to isc dhcp server, now it works.

The suggested keywords are config options, not CLI commands.

Create a new file /etc/dnsmasq.d/99-special-DHCP.conf and insert the following:

dhcp-mac=set:ignore,88:96:4e:e7:ad:22
dhcp-ignore=tag:ignore

then run

sudo pihole restartdns

and you should be done!

Thank you, DL6ER. That seems to have done it however I now get this in my pihole-log:

Jan 1 17:23:31 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored
Jan 1 17:23:31 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored
Jan 1 17:23:33 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored
Jan 1 17:23:33 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored
Jan 1 17:23:34 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored
Jan 1 17:23:34 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored
Jan 1 17:23:35 dnsmasq-dhcp[28918]: DHCPDISCOVER(eth0) 88:96:4e:e7:ad:22 ignored

Tntdruid, your ISC DHCP server solution is intriguing, but I don't know how to change to that. What would that entail?

Thank you both!

You should follow up on this on the mailing list as I'm not sure how to proceed best. We can surely assist you in case the reply is (again) not clear in how to really implement this.