Single /64 IPv6 range with multiple vlans?

[Com_DAC]

My ISP only provides a /64 address and I've got it working just fine on my main network. Does anyone know of a way to make IPv6 available to my other vlans too?

I have reached out to my ISP (Robbers in Canada) and they say they won't give anything larger than /64 so the obvious (and easy) method isn't an option.

[sphbecker]

No, unfortunately doing so would not comply with the IPv6 spec requiring all networks to be at least /64 (and OPNsense does not allow you to violate that).

Something that worked for me (Comcast) is using a prefix hint. On your WAN interface, check the Send IPv6 prefix hint option and then try setting 62 as your delegation size (4 usable prefixes). Apply the changes and wait. I ended up rebooting my firewall and got no IPv6 at all, I figured it wasn't working, but it was late, so I went to bed planning to set it back in the morning. I woke up to find the requested /62 allocation! Guessing Comcast's DHCPv6 lease had to timeout before it would grant a different one.

PS: I would give the prefix hint a try despite what you were told by Robbers. Comcast officially says the same thing, only one /64 for residential customers, but it worked for me and others too. Plus, I kind of doubt the person you talked to even understood what an IPv6 allocation was, he probably just said no to get you off the phone 

[Com_DAC]

Thank you for the reply. I figured as much but thought I'd ask incase there was a way I wasn't aware of. I've tried all the different prefix sizes from 64 to 56 and the only one that works is 64. (Here is one of the threads where I was trying different things: https://www.dslreports.com/forum/r33652078-IPv6-Prefix-Size)

I'll just now have to hope that my ISP eventually implements IPv6 better in the future.

Thank you.