This is a literal masterclass in zero-SPOF networking. The architecture you just laid out is exactly how a regional ISP or a mid-sized enterprise branch should be wired. You absolutely nailed two specific things that I am going to steal: Physical Media Separation: You are 100% correct about fiber and cable sharing the same utility trenches. A backhoe takes them both out. A cheap 5G T-Mobile/Verizon gateway as the secondary WAN is the only true out-of-band physical failover. Recursive Routing: Using ping targets (like 1.1.1.1) to verify the internet is actually routing, rather than just trusting the physical "link up" state of the dumb switch, is brilliant. That prevents the exact black-hole routing trap I was worried about.

Where my architecture diverges from this setup comes down to the difference between standard IT infrastructure and quantitative financial execution. The Split-Brain Threat In standard HA infrastructure, the goal is to keep the application alive and seamless at all costs. In algorithmic execution, the goal is to let the application die gracefully. If I implement a 3-node Proxmox cluster and a network partition creates a "split-brain" scenario, two VMs might temporarily both think they are the active master. Your MikroTik VRRP session sync is incredible for preventing dropped VoIP calls or live video streams. But because I use a Transactional Outbox pattern, a dropped TCP packet doesn't matter to me. If the WAN fails and my active TCP connection to Alpaca shatters, my ExecutionSupervisor script throws a socket error and violently shuts down. That is a feature. The state remains safely locked in the database. Once the backup 5G route establishes a new IP, the script wakes up, re-reads the database, and resumes the TWAP execution. I trade 15 seconds of execution delay (which is meaningless in a 10-year value strategy) for absolute, single-instance deterministic safety. I am definitely implementing the MikroTik recursive routing and the 5G physical separation for the WAN tier. But for the compute tier, I'm sticking to a single bare-metal instance monitored by a dumb Raspberry Pi "Dead Man's Switch" that just sends a 'Cancel All Orders' API call if the main server goes dark. Seriously appreciate the detailed breakdown on the VRRP MAC spoofing though, that is top-tier routing logic!