Possible problem with Switch rt305x - LAN disconnecting

I have recurring situation with a TP-Link C20 v4 running SNAPSHOT, r10348-577174cf60 which has switch driver rt305x-esw and is randomly loosing connectivity to the LAN ports, but the Wifi remains working fine.

What I observed when the problem occurs is that looking at Network, Switch the only port with a cable connected and which was previously negotiated at 100Mb, is then negotiated at 10Mb. If I disconnect and reconnect the cable to another port the new one negotiates again at 100Mb and connectivity is restored.
This occurs randomly during the day using passing or not traffic through the router.

It may seem a specific suspect (rt305x-esw) but perhaps someone else was able to observe this behaviour as well or has any hints about what could be tried to rule out the issue.

I have the same issue with three of my Router
I got, ZBT WE1326, Mi 4A, Mi 4C they all having same issue.