Be careful using Apple wireless diagnostic package, uses a lot of /var/tmp 
space on a small Macbook air 128ssd

Col

 
> On 29 Oct 2020, at 17:24, colin johnston <col...@gt86car.org.uk> wrote:
> 
> This does seem to be solved with the checksum disable below, or at least 
> pings down to sub 10ms on Mac book air with Catalina beta 10.15.6, why aim 
> performs far better I don’t know. I tried to introduce load after cksum 
> disable and it did not see ping spikes as before
> 
> How do we now explain to Apple to fix ?
> 
> Col
> 
> 
>> On 29 Oct 2020, at 14:08, J. Hellenthal via NANOG <nanog@nanog.org> wrote:
>> 
>> I believe I have seen the same thing with a Mid 2015 11,4 running catalina. 
>> Not diagnosing further because I could not find a reason for it fast enough 
>> and not sure if it really had an impact at the moment…. but could you try 
>> the following 
>> 
>> 
>> sudo sysctl net.link.generic.system.hwcksum_tx=0
>> sudo sysctl net.link.generic.system.hwcksum_rx=0
>> sudo ifconfig en0 -rxcsum
>> 
>> 
>> in reverse … to restore the settings 
>> 
>> sudo sysctl net.link.generic.system.hwcksum_tx=1
>> sudo sysctl net.link.generic.system.hwcksum_rx=1
>> sudo ifconfig en0 rxcsum
>> 
>> 
>> If you have some specific tests to run I would be willing to run them here 
>> on Big Sur with the same laptop but I have nothing now that runs Catalina
>> 
>> 
>> Wireshark used to in Catalina rack up cksum errors a lot while these were 
>> all at their defaults.
>> 
>> 
>> 
>>> On Oct 29, 2020, at 08:23, Mark Tinka <mark.ti...@seacom.com> wrote:
>>> 
>>> 
>>> 
>>> On 10/29/20 15:04, Cory Sell wrote:
>>> 
>>>> Might be worth disabling each AP to see if there's one out there having an 
>>>> issue playing nice with the MacBook. Also try different combinations of 
>>>> two APs working together. It's possible the MacBook is flip flopping 
>>>> because the power levels are fighting each other.
>>> 
>>> Tested all that, as well as dropping Tx power levels on each of the AP's to 
>>> Low so that there isn't any power coming from any other AP (despite being 
>>> quite far, already).
>>> 
>>> And to confirm, when the laptop locks into an AP, it doesn't try to join 
>>> another one. When in range, power is very good (between -37dB and -52dB). 
>>> When I walk away, that AP becomes too far (as bad as -80dB), but the next 
>>> one close by is far better (same good values as before) and laptop connects 
>>> and sticks to that.
>>> 
>>> Again, only impacts Catalina. No other Apple device, or the Windows PC that 
>>> is on the same WLAN.
>>> 
>>> 
>>>> Does the Mac have this issue at your local coffee shop or another 
>>>> establishment with Wi-Fi? You can try to rule out the AirPort card in the 
>>>> Mac itself.
>>> 
>>> Never tried, I generally work from home. If I'm out, it's faster to tether 
>>> to my 4G service rather than any public wi-fi.
>>> 
>>> Mark.
>> 
>> 
>> -- 
>> 
>> J. Hellenthal
>> 
>> The fact that there's a highway to Hell but only a stairway to Heaven says a 
>> lot about anticipated traffic volume.
>> 
>> 
>> 
>> 
>> 
>> 
> 

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