If you can't, well then... We're stuck.
Because you have no CDN, all the bots are coming directly to you.
Because that's no CDN or distributed WAF, they're hammering your box.
Because your IP is directly exposed, you're also showing up on Shodan.
Your server may have enough CPU and RAM to handle the load, but does your monthly bandwidth allocation with your provider?
Many are finding previous bandwidth limits (starting around 10TB/month) are no longer enough.
My single static webpage with no updates in 3 years is doing that, which is (one of the reasons) how I end up where that site (and many others in business and personally) is.
You're chasing a dream for a world that doesn't exist anymore.