The verdict

CPU
Beelink SER5 MAX has 1.1x the CPU throughput (20,474 vs 18,159 PassMark).
Plex
Beelink EQR6 transcodes more 4K HDR streams (~5 vs ~3).
Networking
Beelink EQR6 has more NICs (2 vs 1) - better for a firewall or VLAN trunk.

Which wins for each job

Job Beelink EQR6 Beelink SER5 MAX
Plex / Jellyfin ~5 streams win ~3 streams
Frigate NVR add a detector add a detector
Proxmox / VMs 18,159 PassMark 20,474 PassMark win
Firewall / router 2 NICs win 1 NICs
Local AI / LLM no slot no slot

Approximate - capacity estimates from curated specs, the same logic as the recommender. Verify against your exact setup. Prices move; check the retailer.

Full specs

Spec Beelink EQR6 Beelink SER5 MAX
Price (list) $279 $279
CPU AMD Ryzen 5 6600H AMD Ryzen 7 5800H
Cores / threads 6 8
PassMark 18,159 20,474
iGPU Radeon 660M (RDNA2) Radeon Vega 8
NICs 2 1
NIC model Realtek RTL8111 Realtek 1GbE
RAM max (GB) 64 64
M.2 free 1 0
PCIe slot none none
Idle (W) 10 10
TDP (W) 45 54