There's no direct connection
Note: This post is spoiler-heavy, and using spoiler tags would make it rather cumbersome. If you don't wish to find spoilers, this probably isn't the answer for you.
Ragnar from "The Last Kingdom" is Ragnar Ravnson. Ravn being his father. Ravn is the blind man Uhtred meets and cuts food for shortly after being captured. ...
Having looked at that sequence, I see, at the table, there are brown wooden bowls, and in the background, on shelves, much lighter-colored bowls.
There's nothing about them that suggests plastic or even glass.
It could be a much lighter-colored wood. Here is a pine bowl -
Here is a maple bowl -
Ceramics and tinted glazes have been around for thousands ...
Ragnar Lodbrok (legendary - probably real but embellished in history) was a founding father of the viking raiders and settlers in England and France.
Ragnar Ravnson (fictional) was the adoptive father of Uhtred (also fictional) in Bernard Cornwell's books.
Ragnar Lodbrok had a number of sons, including Bjorn, Ivar, Halfdan, and Ubba (kinda maybe). The ...
I think that Vikings takes place a bit before The Last Kingdom.
Why? Well in Vikings, Athelstan had a son, did he not? That son is to become Alfred the Great, but in the show he is just a baby. In "The Last Kingdom", Alfred is well into adulthood. So it could take place a good twenty years+ after the last we've seen of Vikings.