Ping IPv6 invalid characters

[Markfree]

RT-AC86U version Merlin 384.12.
I was trying to ping an IPv6 address using my network tools interface...

If I try to ping an IPv4 address, I can ping without a problem.
Also, pinging IPv6 (like ipv6.google.com) domain name has no problem.

But, when I use an actual IPv6 address on "target" box, it says "Invalid characters of domain name is ':' !".

Why is that?

Thanks guys.

 

[RMerlin]

Based on the error message, I'd say just because the webui was intended to validate for a hostname, not for an IP address.