The problem I have now is that all known speed testers are reporting a low effective TCP upstream speed: I’ve tried speedtest.aa.net, testmy.net/upload and the Ookla speed tester speedtest.net and between them they report 0.29 - 0.6 Mbps, whereas ~1Mbps is expected.
Modem 3 is currently turned off because of the packet loss problems that I have been having, and these measurements were made with that modem off, and my expectations are adjusted accordingly.
Live sync rates:
#1: downstream 2593 kbps, upstream 666 kbps
#2: downstream 3052 kbps, upstream 534 kbps
#3: off
#4: downstream 3247 kbps, upstream 582 kbps
I’m wondering if the slowness could just possibly be due to the exceptionally high rate of modem 1, sounds very unlikely but that’s the only obvious thing that has changed.
Efficiency: sync rates 666+534+582 = 1782 ; adjust for protocol efficiency: 1782 * 0.88 = 1568 expected IP rate, which needs to be slightly downgraded further to allow for IPvx and TCP overheads. So we are a long way short of the expected TCP combined upload speed.