So I thought a bit more about the probably ds-lite/baby-jumbo-frame situation on your link, and I realised that with the modem doing the PPPoE/ds-lite interactions your router does not really know about this, so the calculations should be actually like the following:
But at the sam time you should set the overhead to 80 bytes!
Applying this logic to the new sequential numbers this would get you to:
2.71 / ((1474-14-20-20)/(ceil((1474-14+40+40+8) / 48) * 53)) = 3.337 Mbps
0.60 / ((1474-14-20-20)/(ceil((1474-14+40+40+8) / 48) * 53)) = 0.739 Mbps
Again with ATM(80), but I really believe that your ping variations are most likely caused upstream of your modem, so an adaptive method like Gargoyle's (which is free AFAIK) or the IQ router's might be the best fit for you problem...
Yes, as far as I know this is exactly what they do, automatic Speedtests to automatically adjust the shaper settings to the real conditions. Add to this notifications for updates, it is hard not to like the iqtouter. This is what I recommend for non-nerd family and friends, and people who just want a working router without having to constantly fiddle with in general. It is the iqrouter or the Turris Omnia for slightly more ambitious users, both solutions with a solid OpenWrt basis and automatic update/update notification systems to reasonable security an achievable goal. My immediate family probably wishes I would practice what I preach here, but OpenWrt Master is ever so tempting
Is there a script that makes an adaptive SQM? I would like to try or see if there is something like that, because this would be more useful for 4g links that are unstable than for fixed lines, although I use adsl there are not usually so many variations, but some variations do occur and this, as far as I understand, is a dynamic configuration of SQM works better.
