Hi all,
It's been a while since I last used the ASUS DSL-AC68U. If anyone remembers, I was the person who discovered the various commands that overrode the downstream configuration via TC (e.g. forced fastpath with 80Mbps downstream no matter what the DSLAM said) on VDSL2/FTTC.
Well, after so many firmware updates since I last tried it I thought I'd try it out again and initially with default settings it's sadly no different to what it was the last time I tried it on an ECI DSLAM without G.INP support. However, I've observed after tweaking around with the settings that
bitswap being enabled seems to be causing the instability. It's not concrete so far since I need more time to be 100% certain but it seems to certainly help if I actually disable bitswap. I've barely had CRC errors for a quite some time with bitswap disabled, compared to a much higher amount of CRC errors potentially resulting in loss of sync as soon as bitswap is enabled.
At the time of writing this post I'm now testing:- DSL modulation: VDSL2
- ANNEX Mode: Annex A
- DLA: disabled
- Stability Adjustment: 10 dB
- VDSL Profile: 17a multi mode
- Bitswap: disabled
- SRA: disabled
- G.INP: enabled (though not supported on ECI at this time)
- G.vector: disabled
- ESNP: stable
- RX AGC Gain Adjustment: stable (394)
- Tx Power Control: -3 dB (though I don't think Tx Power Control has anything to do with the downstream instability, eventually I will try it disabled)
This is using firmware:- DSL Firmware Version: 1.0.4.1
- DSL Driver Version: FwVer:5.5.2.7_A_A60901 HwVer:T14.F7_0.1
Interestingly two other posts I came across on other forums have had similar observations with bitswap. If it's true then it's not really the MediaTek chipset that's at fault but rather the algorithm it uses for bitswap is poorly designed. Those on G.INP won't notice problems however since G.INP will correct them fairly quietly.
I will continue testing for another 24-48 hours or so with the current settings. After that I will lower the SNRM target to 9 dB and observe how CRC errors are for another 24-48 hours.
Hopefully someone still with an ASUS DSL-AC68U might find this information useful. I'll post another update soon.