So, if anyone attempts to load Rancher 2.6 on Debian 11 it will fail. I found a bug report on the Rancher GitHub that indicated the issue occurs with because of problems with Docker. So, this is an article to combine all that I have done to correct the issue and all known issues I have seen related to Kubernetes and Debian 11.
Other Info
Fix Grub
Well, this is an easy fix.
sudo nano /etc/default/grub
# Now add the items to like below...
# GRUB_CMDLINE_LINUX_DEFAULT="<whatever was here>[space]systemd.unified_cgroup_hierarchy=false[space] systemd.legacy_systemd_cgroup_controller=false"
#note: items on this line are separated with a space and overall enclosed in quotes.
# this is my line when fixed.
GRUB_CMDLINE_LINUX_DEFAULT="quiet systemd.unified_cgroup_hierarchy=false systemd.legacy_systemd_cgroup_controller=false"
#now that the line is fixed lets update grub
sudo update-grub
#Now on to iptables fix Fix iptables
iptables Fix is for ipv4 only
When making changes make sure the changes are on IPv4 not IPv6 or all options in sysctl.cnf file there are other options that need not be messed with in sysctl.cnf. I have only tested by changing ipv4 as all other info has indicated this is the only stack of ip that is impacted by the problems this post attempts to address. You have been warned!!!
Also, I found this helpful to get Calico to work on my system.
sudo sysctl -w net.ipv4.ip_forward=1
sudo cat /proc/sys/net/ipv4/ip_forward
#modify the setting in /etc/sysctl.conf find the item in there and remove the # in front of it. Oh, and make sure it is the ipv4 not the all one below it or for ipv6 as far as I am aware this only impacts ipv4.
sudo nano /etc/sysctl.confTest it by rebooting and doing the cat again sudo cat /proc/sys/net/ipv4/ip_forward
Conclusion
Overall, simple fixes. I think this is a similar issued with the latest ubuntu as well. However, I do not use ubuntu often and have not tested it as of yet.