Is that so? At least Telekom doesn't do that for IPv4 anymore. They do have a 24h dynamic prefix for IPv6 though (which feels very weird, considering they stopped doing that for IPv4)

The ephemeral IPv6 addresses are just the IPv6 privacy extensions at work. They're just following RFCs

I guess their router stack provides this for free, while the "Zwangstrennung" (disconnect every 24h) was implemented somewhere on their side. So it's actually easier now for them

Partially. Telekom keeps up the line for months at a time. I guess that is due to telephony being done via VoIP, and they don't want to interrupt your late night calls.

Others, even Congstar (which is a cheap telekom brand), do 24h disconnects with a new v4 address, and no v6 at all.

The DSL I use gives me a fixed v4 and v6 range, but still needs to do the daily disconnects.

how do you know what ALL of the them do??