CF upgraded me to 2.5Gbps because they refused to remove CGNAT from my 1Gbps package when renewing.

As title, I have been with CF for 2 years on the 1Gbps package without CGNAT. (I was on CGNAT initially and I requested to be taken off which was granted)

I have been very happy with CF on 1Gbps without the CGNAT. Speed has been good and consistent with very little outages over the course of 2 years. My contract is up for renewal and I just wanted another 2 years of the same service, but they told me I would (most likely) be put back on the CGNAT. I requested to not be put back on it, and after some back and forth, with them saying they could probably do it, eventually they said no it was not possible, and the only way to not be on CGNAT would be to upgrade to 2.5gbps. They offered me a very generous discount on the 2.5gbps package to avoid CGNAT so I accepted.

Now I am realising that this new package uses a new router and I am unsure if my current setup of multiple Linksys AX4200 in a mesh will work with it? I am assuming not.

Can I just continue using the old router at 1gbps? (quite happy with this speed) If I switch to the new router, can I connect my old routers to it in a mesh?

Is the new router a big upgrade over the Linksys ones? I heard they are even more locked down and you cannot even change ipv4 DNS, which seems insane to me? I usually change DNS as one of the first things on a router.

Thanks!