I don't know what other ISPs do, but on AAISP the router IPv6 public address is static, and not related in any way to the user's /48 or pre-allocated /64 within that. "2001:8b0:1111:1111:0:ffff:[your IPv4 WAN in HEX]".

They then route IPv6 traffic for the /64, or any others you set up in the correct way, to that WAN address.

That WAN address is pingable as long as your router is set to respond.

Zen are a good ISP in my experience. I like their network and I know they have invested heavily in it. I can't say for sure but it seems like their new Huawei based network employs some great traffic queuing algos, helping keep stuff flowing without shaping or filtering.

My only complaints are that 1. They switched my backhaul from BT to TTwithout letting me know, and 2. Their service is not as personal as it used to be. E.g. emails on the same subject don't get allocated to the same service technician. This can also be a positive as some are much better than others.

My line has an intermittent problem which causes the speed to drop. They reset the DLM everytime without quibble but aren't super proactive about diagnosing and fixing the underlying issue. To be fair, I haven't really pushed them to yet as am still ruling out changes at my end.

If your line is reliable and you don't mind being with an upper end of mass market rather than a truly boutique provider, you can't do better.

That is probably going way beyond the OP's questions!

You may not be aware but the Fritz box Zen currently supply sees repeated pings as some sort of attack and after a while throws a hissy fit and stops responding to the pings which is why we have to resort to pinging devices inside the LAN.

I don't want to argue with you j, you're trying to help but I get the distinct impression from the OPs replies that you're confusing him. Some of the questions appear naiive whereas your replies are quite techinical and not always appropriate - the smart tv reply was somowhat niche. As you say "I made the reasonable assumption".There's nothing wrong with an assumption so long as you say what it is, if you don't then only you know what it is. If you were to say "assuming that you are trying to access your pc remotely then..." or "assuming you want to control your tv with an Android app then..." then we'd all know what you're assuming and there'd be nothing to quibble about. As it is I think you're confusing the OP, you think you're not. There's room for doubt.

John

Two points - Zen DON'T insist you use the Fritz!box and in any case there is nothing whatsoever wrong with it OR the ISP.

I was aware of that, but if you re-read the OP the main questions were somewhat wider than the Fritz box. It read to me as if that was the least important.

My post also raised the question of how the IPv6 addresses are allocated in the first place, covering this question and in effect asking others to say what other ISPs including Zen do.

In reply to a post by zelly:

Sorry for the newbie questions. If my computer is always on, will that have the static ip address they give us, or is that given to the Fritzbox itself?

AIUI the OP is wondering whether to use the Fritz box or some other if they move to Zen.

In reply to a post by chrisjam:

They switched my backhaul from BT to TTwithout letting me know ...

When they switched me between those backhauls (years ago) they actually sent me a "Sorry you've decided to leave" letter. I was pretty alarmed!

Well they didn't do that this time, but I happened to do a check on the BT availability checker and it said that my line had a termination order on it. This was right at the start of covid when we were working from home. I wasn't super confident but it was all fine. The TT backhaul has a tiny bit more latency but only by a millisecond or so. Still, it would have been nice for them to send me a note to say they were making changes.

In reply to a post by chrisjam:

The TT backhaul has a tiny bit more latency but only by a millisecond or so. Still, it would have been nice for them to send me a note to say they were making changes.

Funnily enough I was just writing here about my similar experience moving FTTP service over to TTB with their backhaul from a BTW backhaul. About a 1 to 2ms difference in latency. Not that it really matters in real world - unless your extreme gaming or running some massively sensitive algorithmic trading platform 🤣