Open source devs hitting 3 hard walls when fine-tuning LLMs on distributed hardware:

1. Memory fragmentation across nodes - most frameworks can't efficiently shard model states beyond simple data parallelism

2. Network bandwidth choking on internet connections - gradient sync and activation passing eat bandwidth that consumer ISPs can't handle

3. Node failures nuking entire runs - no fault tolerance means hours of compute wasted when one machine drops

Current frameworks (DeepSpeed, FSDP, etc.) assume datacenter-grade infra. They're not built for heterogeneous home setups where one node has 24GB VRAM, another has 12GB, and they're connected over residential fiber with 100ms latency spikes.