But I give up. I cannot figure out how this thing works. All the how-to pages that I found essentially have the same examples, copied from the nftables distribution. They are all trivial or incomplete. I doubt that anybody who has written those how-to pages has ever run nftables in anger. The netfilter mailing list was of some help, but only some.
And if you read this, and have nftables running on a router that does masquerading, please post your full configuration in the comments. Thank you.
In the meantime, it’s back to iptables.