Documentation “How to configure static IPs”: Ping between instances does not work

Description of documentation issue or suggestion I followed the documentation https://multipass.run/docs/configure-static-ips to set up a bridge network on the host, and to launch two instances, and to connect them to the bridge network. The documentation suggests that I can ping from one instance to the other. However, this does not work. Ping from between host and instances works, respectively.

Host: Ubuntu 24.04 Multipass version 1.14.1

Citation of relevant part of the documentation:

Step 6: More instances If desired, repeat steps 2-5 with different names/MACs/IP terminations (e.g. 10.13.31.14) to launch other instances with static IPs in the same network. You can ping from one instance to another to confirm that they are connected. For example: multipass exec -n test1 -- ping 10.13.31.14

Proposal to fix issue or enact suggestion I assume that some routing configuration might be missing on the host machine.

Additional context Relevant documentation page: https://multipass.run/docs/configure-static-ips

Host network config

host $ ip a
[…]
7: br-test: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 16:31:ed:bb:72:08 brd ff:ff:ff:ff:ff:ff
    inet 10.13.31.1/24 brd 10.13.31.255 scope global noprefixroute br-test
       valid_lft forever preferred_lft forever
    inet6 fe80::cfdb:a26f:410a:d462/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[…]

host $ ip route
default via 192.168.2.1 dev enx806d97190830 proto dhcp src 192.168.2.160 metric 100 
10.10.229.0/24 dev mpbr0 proto kernel scope link src 10.10.229.1 
10.13.31.0/24 dev br-test proto kernel scope link src 10.13.31.1 metric 425 
10.91.21.0/24 dev lxdbr0 proto kernel scope link src 10.91.21.1 linkdown 
172.17.0.0/16 dev docker0 proto kernel scope link src 172.17.0.1 linkdown 
192.168.2.0/24 dev enx806d97190830 proto kernel scope link src 192.168.2.160 metric 100

Instance “Server” network config

server-instance $ ip a
[…]
3: enp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 52:54:00:4b:ab:cd brd ff:ff:ff:ff:ff:ff
    inet 10.13.31.13/24 brd 10.13.31.255 scope global enp6s0
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe4b:abcd/64 scope link 
       valid_lft forever preferred_lft forever
[…]

server-instance $ ip route
default via 10.10.229.1 dev enp5s0 proto dhcp src 10.10.229.116 metric 100 
10.10.229.0/24 dev enp5s0 proto kernel scope link src 10.10.229.116 metric 100 
10.10.229.1 dev enp5s0 proto dhcp scope link src 10.10.229.116 metric 100 
10.13.31.0/24 dev enp6s0 proto kernel scope link src 10.13.31.13

Instance “Client” network config

client-instance $ ip a
[…]
3: enp6s0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
    link/ether 52:54:00:4b:ab:ce brd ff:ff:ff:ff:ff:ff
    inet 10.13.31.14/24 brd 10.13.31.255 scope global enp6s0
       valid_lft forever preferred_lft forever
    inet6 fe80::5054:ff:fe4b:abce/64 scope link 
       valid_lft forever preferred_lft forever
[…]

client-instance $ ip route
default via 10.10.229.1 dev enp5s0 proto dhcp src 10.10.229.71 metric 100 
10.10.229.0/24 dev enp5s0 proto kernel scope link src 10.10.229.71 metric 100 
10.10.229.1 dev enp5s0 proto dhcp scope link src 10.10.229.71 metric 100 
10.13.31.0/24 dev enp6s0 proto kernel scope link src 10.13.31.14