To provide more info this issue also happens with a win10 laptop (ethernet connected, ipv6 disabled on R3) when put to sleep, approx 15secs or so, and appears to be related to log entries w.r.t. port of interest entering a learning state.
Specifics firmware 4.0.19:
Chrome Web browser: tab1 = dumaos, tab2 = sat with a new.bbc.co.uk entered into url but not executed, i.e. blank tab
Put laptop to sleep
R3 Eth1 port (laptop connected) goes down, and then disabled
Wake up laptop, and press enter on the web url tab to get news... ~15secs delay
meanwhile... logs state
R1 Eth1 reports Link up... auto negotiates... 10Mbps... 1000Mbps
Enters blocked... listening... learning... forwarding state
Daemons running on R3 throw errors: ndhttpd, odhcp6c
This issue is repeatable, with similar errors both times. See log extract below. Eth1 = laptop, Eth3 = xbox
Sim