When on my local network:

• The reMarkable 2 is connected to my router
• But the Cloud Sync does not work at all

This is weird, because sharing the wifi from my phone, the reMarkable 2 Cloud Sync works flawlessly.

After investigating, it seems that IPv6 is the culprit. My router handles IPv6 differently compared to my phone.

The reMarkable 2 does not fallback to IPv4 automatically, so we need to disable it.

Disable IPv6 on the reMarkable 2

1. Plug the reMarkable 2 to your computer, then connect to it over SSH: ssh root@10.11.99.1

For more information, here is a detailed guide

2. Run the following commands to disable IPv6

Disable IPv6 instantly

sysctl -w net.ipv6.conf.all.disable_ipv6=1

Disable IPv6 for future reboots

echo "net.ipv6.conf.all.disable_ipv6 = 1" >> /etc/sysctl.conf