Periodic dropouts

[#1]

Hi all. Been getting lots of dropouts yesterday and today on fibre broadband. Every time it's between 5s and 20s of no connectivity and then it comes back.  Tech log shows one or more ARP events at the exact moment the dropout happens:

11:18:12, 27 Jul.

ARP [add] br0(eth0) 192.168.1.228 42:7c:3f:98:63:e4

11:18:12, 27 Jul.

ARP [del] br0 192.168.1.71 42:7c:3f:98:63:e4

11:18:06, 27 Jul.

LAN [ADD] ARP 192.168.1.247 with 42:7c:3f:98:63:e0 from br0(eth0)

11:18:06, 27 Jul.

ARP [add] br0(eth0) 192.168.1.247 42:7c:3f:98:63:e0

11:18:04, 27 Jul.

ARP [del] br0 192.168.1.247 42:7c:3f:98:63:e4

11:18:04, 27 Jul.

ARP [del] br0 192.168.1.228 42:7c:3f:98:63:e4

I've just updated DNS servers to Google's, to see if this helps.

[#2]

Hmm. Changing the DNS hasn't changed anything. Still getting occasional dropouts.