DHCP failure: NACK

I set up a local DHCP server at home and disabled the DHCP running on my internet provider modem. My laptop, phone & tablet are working fine and are able to get an IP however I have troubles with my sonos wifi speaker: it keeps sending DHCP requests like this:

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192.168.1.62 is the DHCP server. 192.168.1.254 is the modem. I guess the problem is the NACK request sent by the modem (the DHCP server is disabled on it though)... The pcap file is available here: https://ufile.io/vaubc Any idea about what's wrong here?

Thanks.