Can anyone help me diagnose a local wired+wireless network quality/latency issue?

TLDR: Wireless connections between *local devices* have unclear issues, but nothing obvious. Connectivity is fine, but local streaming is bad (bandwidth? packet loss? 🤷🏼‍♀️). Connections between wired devices seem happy as a clam. Wireless streaming UHD to/from cloud is good but not spectacular. The only issue is local streaming between a wireless device and any other device in the network (wired or wireless).

IIRC, modem has DHCP disabled and defers DHCP to the Nest router, because Nest doesn't like anyone else doing DHCP. Probably something is fucky in this ballpark—but the fact that this affects two wireless devices both on the same Nest WiFi may rule out DHCP.

Nest router provides 802.11ac dual band mesh and passthrough cat6. Rest of network is short cat6 other than the 20m cat6 in the walls between the managed and unmanaged switches. Managed switch is currently wide open on one VLAN, to simplify.

Topology:
ISP
↕️
Modem/router/WiFi (disabled DHCP)
↕️
Google Nest Router ↔️ (WiFi) MacBook
↕️ (Wired)
Managed switch ↔️ MacBook (wired)
↕️
Unmanaged switch
↕️
Windows PC

Maybe complicating factors:
★ We have one Nest WiFi point meshed to the router. (Maybe two, but I can't find it.)
★ modem/router runs another wifi channel (not meshed with Nest). Haven't tried disabling yet because I'm lazy and it's unlikely an issue. No difference in connecting the MacBook to this WiFi vs the Nest WiFi. Also haven't tried disabling Nest WiFi and trying only this WiFi.
★ I'm lazy 🙃

#Networking #NetworkIssue #NetworksAreWork #NetworkPuzzle #WiFi #WhyFi