Series 3 Watch. Can’t pair without update, software update fails!

So I bought a series 3 watch when I had my iPhone 8. It worked no problem then I stopped wearing it for months. In that time I got an iPhone 11. Now when I try to re pair my watch, it says “update required to finish pairing” then every time I try to download the update, it says “software update failed”. I’m getting rather frustrated. I’ve tried everything I found online including removing/ erasing watch from find my iPhone and such, just can’t figure it out.