Unable to reach my home server using IPv6

Question

I have a home server on which I run a webserver and occasionally need to SSH into. The home server has an IPv6 addresse as can be seen below:

$ ip -6 addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN qlen 1000
    inet6 ::1/128 scope host 
       valid_lft forever preferred_lft forever
3: wlp28s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
    inet6 2405:201:100f:e89f:1a89:e83:3958:25c6/64 scope global temporary dynamic 
       valid_lft 3560sec preferred_lft 3560sec
    inet6 2405:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:6ee3/64 scope global dynamic mngtmpaddr noprefixroute 
       valid_lft 3560sec preferred_lft 3560sec
    inet6 fe80::5ad4:f50a:732a:d729/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
5: docker_gwbridge: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP 
    inet6 fe80::42:aaff:fec9:3df6/64 scope link 
       valid_lft forever preferred_lft forever
11: veth707599e@if10: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP 
    inet6 fe80::2cd8:4dff:febb:594d/64 scope link 
       valid_lft forever preferred_lft forever

(I have masked out the MAC-based IPv6 for privacy purposes).

I have a DigitalOcean droplet from which I tried pinging both temporary as well as dynamic IPv6 address as follows, but no avail:

ping6 2405:201:100f:e89f:1a89:e83:3958:25c6
ping6 2405:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:6ee3

I also tried running a simple Python HTTP server and reaching it over VPN, but no avail:

$ python -m http.server --bind ::
Serving HTTP on :: port 8000 (http://[::]:8000/) ...

Firing up Chrome/Firefox and connecting it to VPN and then typing http://[2405:201:100f:e89f:1a89:e83:3958:25c6]:8000 or http://[2405:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:6ee3]:8000 gives me The requested URL could not be retrieved error.

The home server does not have any Firewall. It's a bare-bones, fresh Ubuntu installation.

What am I missing?

Thanks!