Unwanted attempts at Port Forwarding

[#1]

The following is a snapshot from my router event log. 192.168.1.184 is an Amazon Echo, 192.168.1.193 Is a Chromecast.

Both seems intent on setting up Port Forwarding to either Google's DNS server or my deafault OpenDNS one.

From what I can see, both are being rejected indicating that port forwarding is not required. Can any-one advise why this is happening and whether it can be stopped?

I don't need to access either of these devices from outside of my home network. Presumably one way is to set up port forwarding but why should I and what are the security implications?

[#2]

My guess @Baldrick1 is that the devices are trying to configure themselves for Push Notifications, you can turn them off on the Echo but as for the Chromecast I don't know as I don't have one. Try the Echo first to see if the entries stop appearing in your log.

[#3]

@Mook 

Thanks for your suggestion, but it doesn't seem to have stopped the rot.

I have gone onto energy saving Plan B, that is switching the damn things off unless I need to use them.

[#4]

You should be able to stop that from happening by switching off UPnP (Universal Plug n Play) on your router.

[#5]

P.S. This 'Security Now' video by Steve Gibson explains all.

https://www.youtube.com/watch?v=RMuR7y2VujY&feature=youtu.be&t=86 

[#6]

@markuswelby 

Thanks for the suggestion but UPnP is Off. I don'i know if that or the enhaced security tab is implicated in preventing a port forwarding rule being set up.

[#7]

Most strange.....

I wonder if switching off Extended UPnP Security (I'm sure this only needs to be on if the UPnP is on) and restarting the hub would help?