From: tauno.voipio@notused.fi.invalid   
      
   On 5.2.2026 16.27, The Natural Philosopher wrote:   
   > On 05/02/2026 14:04, Lars Poulsen wrote:   
   >> On 2026-02-04, The Natural Philosopher  wrote:   
   >>> If you remember I had constricted a bridge from wifi to ethernet to act   
   >>> as a bridged access point. On a PI 4B as a test platform   
   >>>   
   >>> The problem was that whilst the bridge was reasonably OK accessing my   
   >>> LAN, up to 90% packet loss was experienced when accessing the internet   
   >>> via my edge router.   
   >>>   
   >>> Two further points have been established but the exact reason for the   
   >>> behaviour still remains a mystery   
   >>>   
   >>> 1/. A friend with a Pi 5 attempted to duplicate the setup, could not get   
   >>> it to work and instead used the Network Manager  GUI to set up  a   
   >>> (routed?) access point which worked ok. It turns out that you cannot use   
   >>> the GUI tool to set up a bridge at all. Only nmcli.   
   >>>   
   >>> 2/. After a long time with traceroutes and pings I realised that this   
   >>> particular machine was the *only one wired directly to the router via a   
   >>> single gigabit Ethernet cable*. Everything else went via an ancient   
   >>> 100Mbps switch that I inherited from an office clearout. In a rash of   
   >>> 'well I tried everything else' I unplugged the Pi from the Gigabit   
   >>> router socket  and put it into the 100Mbps switch and bingo!... Pretty   
   >>> decent internet performance. Yes extremely long transfers sometimes   
   >>> fail, but its very useable   
   >>>   
   >>> What I cannot for the life of me understand is *why*  this worked. The   
   >>> same [Gigabit] link was involved in both local and Internet access.  The   
   >>> only difference being that local access ALSO went through a 100Mbps   
   >>> switch.   
   >>>   
   >>> If anyone can shed light on this I would appreciate it.   
   >>>   
   >>> If it matters, the router is a Draytek Vigor2762Vac running PPPoE via an   
   >>> Openrach ONT to an optical fibre for Internet and thence to the ISP.   
   >>   
   >> The link-level connection involves a negotiation handshake to find   
   >> compatible parameters. You may read up on MII (Media Independent   
   >> Interface). When the state machines in the MII part of the MAC block in   
   >> the Ethernet part of your SoC chip encounters an MII state machine it   
   >> has not seen before, there may be timing dependent glitches.   
   >> One of our customers has an installation on a remote island where   
   >> the link between a microprocessor in his seismic gear connected via an   
   >> ethernet switch to our radio locks up every 6 to 12 months and needs a   
   >> remote-triggered power cycle to reset. We suggested he try another   
   >> switch next time he can get a service tech to the island.   
   >>   
   >> It is also possible that a port data rate of a Gigabit may occasionally   
   >> cause bus contention on some internal data bus in the PI triggering   
   >> a bus error, while 100Mbps avoids that contention. I have seen such   
   >> bus contention cause glitches in memory controllers in a few systems   
   >> over my career.   
   >>   
   >   
   > Thank you for that.   
   >   
   > Since the pi was always connected via the gigabit and the router   
   > hardware, and performed well when then routed by an external switch,  it   
   > seems unlikely that it was the PI<=>router link that was at fault.   
   >   
   > I am leaning more towards the router buffering Internet data into large   
   > Gigabit Ethernet bursts that overwhelmed the Pi when it was forwarding   
   > to wifi. Limiting the data rate to 100Mbps allowed the Pis Ethernet to   
   > function well enough not to overload the wifi.   
   >   
   > It was only the Internet<=>Router<=gigabit=>Pi4<=wifi=>client that broke   
   >   
   > Without the wifi the ethernet was OK., Without the gigabit the wifi was OK.   
   >   
   > Anyway I think we both agree that it is not something that can be   
   > programmed around . I will test again when I get a Pi 5 and if it still   
   > sucks, a wifi access point is not that expensive. The Pi is also pretty   
   > crippled in wifi speed.   
   >   
   > I suspect the  PI wifi hardware was never really designed for AP usage:   
   > More for client access to a Wifi station.   
   >   
   > I may try adding a wifi dongle at some point   
   >   
      
   It may be as simple as the cable from your router to the Pi, if it   
   is a different one than with the switch. Verify that you're using   
   a CAT6 patch cable.   
      
   I'm running a Zyxel GS-1200 switch with gigabit ports to a Pi3B+   
   and WLAN bridging without extra problems. The WLAN in Pi is not   
   completely as good a radio than a dedicated WLAN base station,   
   due to different antenna systems.   
      
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