From: tnp@invalid.invalid   
      
   On 05/02/2026 19:44, Tauno Voipio wrote:   
   > 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.   
   >   
   Well the cable worked fine for all other traffic except wifi traffic *to   
   the internet*  so I doubt that it is the problem.   
      
   > 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.   
   >   
   I am going to back burner this project until I can get a pi 5 (at a   
   reasonable price. RAM is just silly right now) and if it doesn't work   
   properly use a dedicated wifi unit. I may try with a dedicated wifi-USB   
   dongle   
      
   My conclusion is that I had arrived at the correct software setup, but   
   the hardware or firmware was an issue. Since I can't change either in   
   practical terms apart from trying a wifi dongle  the matter tests where   
   it is.   
      
   --   
   Civilization exists by geological consent, subject to change without notice.   
     – Will Durant   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)