We actually use a complex server structure. SmartMixer uses several servers, which have different tasks to do. As we use a modular server structure we ensure our users and anyone who interacts with SmartMixer more anonymity and safety. That’s why it’s a crucial argument for some of our users, as it play a huge role.

The Internet is fundamentally broken. We need DDoS protection at the network layer, or else you're going to continue seeing 99% of the Internet hiding behind a few centralized third-parties. It's absolutely ridiculous. Realize also that Cloudflare can see all traffic unencrypted. They're almost certainly an NSA honeypot already, but even if not, their many screwups make them unworthy of this kind of trust. (Their Argo tunnel doesn't fix this trust issue at all, BTW.) However, since the Internet is broken fundamentally, mitigating it is too difficult for it to be a good idea for me to devote resources to it at this time.

I don't have time to work on this at all, but if someone created a non-profit dedicated to producing decentralized anti-DDoS solutions, I'd donate to it. On github I see two very immature projects in this area:
 - gatekeeper is intended for large organizations, and blocks attacks at the network/transport layer. However, I've found that SYNPROXY gateways plus upstream UDP blocking is sufficient for this on bitcointalk.org's scale, and gatekeeper also requires access to BGP, which isn't common unless you're pretty big.
 - AntiDDOS works at layer 7, which is where my homebrew DDoS protection broke down. But it doesn't have a good IP classification system, it's based on (and assumes the existence of) a single final application server, and it's too simple/incomplete overall.

(BTW, this problem is an example of centralization being used as an ever-increasing crutch for systems that are technologically flawed. It has parallels to scaling of cryptocurrencies and other supposed-to-be-decentralized systems.)