M 4 Mini ethernet/wifi issue

Simon Rob P wrote:

Wi Fi and Ethernet both enabled and priority set to Ethernet first. Have to unplug ethernet - connection to web page then works.

Step 1 to diagnose the problem -

Turn off WiFi in the M4 mini, then shut down & restart the mini and see if that clears up the wired ethernet issue. Pls. report back on results.

Step 2 -

Is the "ethernet over mains wiring" a direct ethernet connection from your M4 mini to the TP Link Dec X50 ... or is there an ethernet switch or other device connected between them?

I’d expect the combination of mesh and power-line is dodgy.

Ensure the mesh firmware is current.

Troubleshooting this will likely require network access, and network log access, and a Mac or other Wi-Fi diagnostic tool. Might further require temporarily moving everything onto the same Wi-Fi mesh or AP device, once the mesh or AP and ISP links are tested. Alternatively, temporarily installing wired backhaul for the mesh (assuming the mesh routers support wired backhaul), after verifying that the Wi-Fi is stable and sufficiently dense and not encountering interference. Same temporary wiring for the power-line connections.

I’m unfamiliar with the TP Link mesh gear and its capabilities. Power-line is commonly low throughput, or flaky, or both.

If you have access to a Mac, a tool such as WiFi Explorer is useful for visualizing signals and Wi-Fi interference. There are undoubtedly similar Wi-Fi tools for Windows PC, and handheld tools exist (pricy: Fluke). The mesh itself will likely have at least some logging, RSSI/noise/SNR, and maybe interference detection. Wi-Fi tools for iPhone and iPad are somewhere between limited and non-existent

Do you have a single TP Link Deco X50 unit or a multiple unit mesh setup...?

If you have a single TP Link Deco X50 unit, drop the Power-line adapter and test a Cat 6 Ethernet cable between the TP Link Deco X50 and the Mac mini if possible.

Optionally add a second TP Link Deco X50 unit or.. upgrade to the TP Link Deco X50 multiple unit mesh system.

https://www.tp-link.com/us/deco-mesh-wifi/product-family/deco-x50/v1%20(3-pack)/

If you already have the TP Link Deco X50 multiple mesh setup, move one of the units close enough to the Mac mini for better Wi-Fi and/or a direct Ethernet cable connection.

To add: Check your Ethernet cable(s) and make sure that you are using a Cat 6 or better cable(s).

Sounds weird.

FWIW I have service provider 500/500 fibre → Huawei Echolife → CAT 6 Ethernet → TP-Link Deco XE75 master in Router mode → CAT 6 Ethernet → TP-Link TL-SG105PE switch → CAT 6 Ethernet backhaul → two XE75 slaves in Access Point mode as well as other Ethernet devices connected via CAT 6 Ethernet to the XE75 slaves.

The only nuisance is that Ethernet backhaul resets every few months to Wi-Fi only for the XE75 slaves or otherwise acts up by not giving IP# to some clients (that hasn't happened in recent FWs, though), and I have to power-OFF/ON the switch and all XE75s to make Ethernet backhaul to work again (turning TL-SG105PE switch loop detection function OFF might fix it but I have not yet tried if that fixes it once and for all).

The other minor problem is that my Ethernet & Wi-Fi -enabled (in that order) Mac mini 2018 fails connect Option-Command-R Internet Recovery if Ethernet wire is connected (it just sits there staring at the spinning globe) while via Ethernet wire is disconnected it readily asks password to join Wi-Fi and continue from there.

“Mains wiring”? Power-line Ethernet to the Deco X50 AX3000 Whole Home Mesh WiFi 6 System? Or something else? Power-line Ethernet can sometimes be dodgy, and isn’t usually necessary with a mesh network.

Usual would be a Cat 6 or 6A wired connection — don’t bother either Cat 7 or Cat 8, or with 5e or older — and this wired connection potentially involving a switch, and all probably wired directly into the back of a nearby Deco mesh router.

Ensure the Deco X50 is running Deco X50(US)_V1.6_1.6.7 Build 25031412 firmware from June 2025, or newer firmware as available.

Simon Rob P wrote:

Thanks. It's a 4 unit mesh system. Unfortunately due to the configuration of the house, moving one of the units closer to the mini takes the signal away from one part of the house. As I write, the mini is running on ethernet through a powerline adapter perfectly well; having unplugged after switching on and replugged. It's weird and a pain, but I can live with it. Lokks like I may have to.

Both mesh and power-line connections can be very much unreliable under load, and are subject to sometimes subtle or unpredictable glitches, such as fail when the neighbor runs their microwave, or when the neighbor’s uncoordinated network stumbles into yours and then yours cascades into another and around and around the channels it all goes, or the DFS detects active radar, etc. That’s atop some mesh networks and mesh gear just being flaky, and all mesh networks needing bandwidth and channels for the backhauls.

“It’s weird and a pain” could describe much of wireless networking, even when not contending with the added “fun” of mesh and power-line.

Get a Wi-Fi scanner (WiFi Explorer on a Mac, etc) and look at the local chatter. And do expect power-line to be constrained and to glitch.