Network going down every 10 minutes - broadcast storm? Maybe a loop?

Hi r/networking,

I am troubleshooting a small business network of ~24 devices . - switch is unmanaged 24 port (I know , I tried to convince the owner to get one ) - there are 12 IP phones , the computers are connected through the phones - one NAS , one printer

Every about 10 minutes the whole network comes down , until the switch is rebooted and then it goes down again in roughly 10 minutes . When it's down , wired devices can't get an IP from DHCP nor can they ping other devices on the network. Wifi works OK, can ping other devices and access the router's admin panel. Wireshark shows lots of ARP packets going around . I tried replacing the switch , but the problem persists . I have a feeling that it's a bad device on the network causing a broadcast storm or the network is looped somehow .

Any suggestions on how to troubleshoot ?

Thanks for your help :)