Walled city type series, style of Stephen Baxter/Peter F Hamilton?

I read mainly sci-fi and supernatural in modern day, and some fantasy and romance.
My favourite author is Peter F Hamilton because of his long, epic stories in universes where people are generally decent and the endings lean hopeful rather than bleak.

I am wanting to read a book or preferably series that's
-Set in a walled village/city/region (kind of like Attack on Titan or Pacific Rim) with monsters, horrors, robots or whatever roaming outside trying to breach the walls.

-Either modern day, alternate reality, recent history or near future or post-apocalyptic (Like Terry Brooks's The Druid of Shannara where it's a tech world gone to ruin then magic).

-I'd like the book to include some wall defence either by the character or even in the background like the character watching a TV news show of a wall breach etc.

-Adult or maybe YA

-Preferably not zombies, but ok for zombie based books if they really fit what I'm wanting.

-Ideally less than 20ish years old

Authors I like
Peter f Hamilton – All of it, He's my favorite author, his big scope, writing style, positive stories/endings.
Stephen Baxter – Xeelee series, Flood/Ark, The Long Earth,
Stephanie Meyer – The Host is light and good, Eclipse Saga is good,
Jim Butcher – Dresden Files are great though a little ..90s,
Alistair Reynolds – Revelation Space especially
Terry Prichett – Mainly the joint writings with Stephen Baxter, his other work is a little YA I guess.
Anne McCaffrey – Dragon Riders of Pern (Though read many years ago) & The Ship Who Sang

Books
Red White & Royal Blue – It's fun, well written and light
Zodiac Academy series – Harry Potter but with adults
Melanie Rawn's Exiles trilogy – Just well written and interesting
The Demon Cycle Series by Peter V. Brett – Interesting world, well written

The Gap Cycle Series by Stephen R. Donaldson is well written and I like the series apart from the torture/rape stuff.