Your ISP is refreshing the lease on the IP address. Nothing unusual about that and it can cause a disco depending on how fast they can get the DHCP server to respond.
If the DHCP server response takes too long, a disco will happen. There is nothing that can really be done about it, unless your ISP changes its release/refresh time in the server.
It is the nature of dynamic IP addresses and probably for about 50% of the discos that happen in a game.