Why does multicast or mDNS fail across VLANs?
Discovery protocols are normally local-link. Crossing VLANs needs an intentionally configured reflector/gateway and security policy; simple routing may not be enough.
SonosView original answer
Wi-Fi help
Simple answers to common Wi-Fi questions
Type your problem in your own words below. Every answer says what to check, what to leave alone, and when it's time to call someone for help.
15 answers found · last checked 17 August 2026
Could IGMP snooping break Sonos or IPTV?
Incorrect multicast handling can cause flooding or failed delivery. Whether snooping helps depends on switch/router topology and querier behaviour.
SonosView original answer
Why do some clients fail on DFS channels?
Older or region-mismatched clients may not support all DFS channels, and radar events can move the network. Check client regulatory domain and driver.
Why does a device get 169.254.x.x?
That is a self-assigned link-local IPv4 address, usually meaning DHCP did not provide a lease. Check association, DHCP scope, VLAN and duplicate servers.
Why do I see intermittent duplicate IP warnings?
A manually assigned address may overlap DHCP, a stale reservation may exist, or two DHCP servers may be active due to a second router.
Why is mesh backhaul good but the client still slow?
The client link may be the bottleneck: weak radio, old standard, power saving, interference or driver. Backhaul and fronthaul are separate links.
What causes bufferbloat?
Large queues fill during upload/download, increasing latency even without packet loss. Test idle versus loaded latency and manage heavy traffic/QoS where supported.
CiscoView original answer
Why does TCP test fast but UDP voice/gaming fail?
TCP retransmits and adapts, masking some loss; real-time UDP often cannot recover late/lost packets. Measure loss, jitter and path-specific filtering.
CiscoView original answer
Could MTU cause VPN or website problems?
Yes. Encapsulation can make packets too large; broken path-MTU discovery may cause stalls. Test under the VPN/provider’s approved MTU guidance.
CiscoView original answer
Why does hairpin NAT testing fail from inside my home?
Some routers do not support NAT loopback, so the public hostname works externally but not internally. Test from mobile data and consider split DNS.
Should I use powerline adapters for mesh backhaul?
They may work, but performance depends heavily on electrical circuits, noise and consumer-unit layout. Ethernet is more predictable.
Can radar, microwaves or baby monitors affect Wi‑Fi?
Yes. Microwaves and many consumer devices can raise 2.4 GHz interference; radar triggers DFS channel moves on 5 GHz. Correlate time/location and radio metrics.
Why does Wi‑Fi drop when Bluetooth is busy?
Bluetooth shares 2.4 GHz spectrum; poor coexistence drivers or a congested environment can hurt some clients. Try 5 GHz, update drivers and compare.
PlusnetView original answer
Is a mesh hop expected to halve speed?
A same-radio wireless relay can reduce available airtime, but the actual impact varies with radios, backhaul quality, channel use and traffic. It is not a fixed 50% rule.
Why does Wi‑Fi calling fail while normal internet works?
Wi‑Fi calling relies on the mobile operator’s secure tunnel, DNS/NAT and handset provisioning. VPN, firewall, CGNAT or operator outage can affect it.
OfficialView original answer