I know I should have upgraded earlier, but in my defense (I do software) most updates contain backwards compatibility and bring to up to date. 

The website doesn't have any older firmwares. How can I bring my router to latest?

I assume assumed it was auto updating.

The Web UI says 2021?

Ideally firmware updates contain everything before so you don't need to install mulitple files as that can always be problematic.

Thank you.