Why are bonds returning negative?

I've been reading a book about where to put your cash, and the author often recommends Government bonds and REITS.

I'm based in the UK, so looked into ETFs such as SHY, GOVT, TLT, etc.

But zooming out over the past six months or so, and they're all down 10-20%.

I was thinking they'd be returning 2%+ at least, effectively the same as bank interest.

I'm clearly missing something in my knowledge here. Can anyone explain what I'm missing? (Except a brain, which is obviously a core problem for me.)

I've never figured out how to buy bonds (as ETFs or directly [remember I'm in the UK]) as everything seems to end up returning a negative.