Thank you for providing your feedback.
I will address this limit to the developers.
Could you provide the number of devices affected by this?
As a temporary workaround, configuration details can be modified by SSH, specifically targeting /etc/config/ipsec file.
Since configuration options may differ between firmware versions, I suggest to create a working configuration in the current WebUI by giving any name to the instance within the 8 character limit and edit name in the SSH afterwards. However, make sure the tunnel establishes and configuration is correct, because, as you have mentioned, if instance name is longer than 8 characters, WebUI will not accept configuration changes.
Below are the instructions, on how to modify ipsec configuration via SSH. To login, use command line interface from router's WebUI in System -> CLI page or an SSH client such as PuTTy. Use root as username and router's password to login.
Execute the following command:
Press letter i to enable editing and change every option, regarding either instance name, or configuration details.
Once done press Esc, then enter :wq and press Enter.
Then, execute the following command:
- /etc/init.d/ipsec restart
That should be enough to continue using ipsec.