Cannot Connect To Time Capsule

You are using the MAC address of the TC.. that will not work.

You must use the IP address.. but I have to admit as you noted your situation is a bit different using IPv6.

In Finder.. under shared you should see the TC, try and mount it directly in the Finder window .. without manually trying and see if you can then access the hard disk.. once you get the TC disk mounted in Finder it will usually work in Time Machine.

Otherwise I try the same command SMB://IPv6 IP address.. and if that doesn't work still use the IPv4 should work fine in your local network.

You have both WIFI and PADSTIMECAPSULE connected. Are both on the same network (ie. is PADSTIMECAPSULE connected to WIFI)? Per your setting, WIFI is set as first priority. If the two are not on same network, you may try again by rearranging network order, put PADSTIMECAPSULE first.

Again, as mentioned by LaPastenague, you need to use IP address (IPv4 or IPv6), not MAC address.

I assume you are saying WIFI and PADSTIMECAPSULE are actually the same thing?

I'm not familiar with IPv6, a bit surprise to see that you have 2 wireless connections concurrently - either you have 2 WIFI cards or something to do with IPv6?

If I'm not mistaken, when there are 2 connections on Network setting, the one on top takes priority. For example if I have WIFI and Ethernet connected - WIFI is to router > Internet (IP 192.168.0.xxx) , Ethernet to another PC (peer-to-peer) and assuming the PC it is not connect to WIFI router (IP 192.168.1.xxx), I get internet connection but won't be able to see the other Mac - even though both machines are physically connected via Ethernet. If Ethernet on top, won't be able to connect to internet but able to link up to the peer PC.