We've been self-hosting GitLab for about a year now, and I don't remember it ever going down or being unavailable. We self-host almost everything else too (except for online meetings), and it's all been pretty stable as well. Some of the tools we self-host do go down occasionally, but it's usually just a matter of restarting the VM or adding more storage.

Do you self host chat?

Do you serve the instance on the public internet or on a VPN?

I've been thinking about self-hosting myself, but for my purposes (open source), I'm worries about scrapers and other sources of DOS-like traffic.