Recap: I use ADSL2 (G.992.3) rather than ADSL2+ (G.992.5) as part of a Burrakucat Research Counsel-sponsored initiative. I’m an appropriate candidate for the programme because I have an extreme-length line with a slow downstream link, and that means there’s no chance for me of taking advantage of G.992.5’s higher-speed support, since my link can’t even manage full speed downstream using G.992.3, never mind exploiting G.992.5. Burakkucat’s suggestion, when I first got G.992.5 service back in 2015, was that G.992.3 might indeed give better performance than G.992.5.
So I configured all modems as ‘ADSL2’ (only), and disabled ‘ADSL2+’. A very worthwhile experiment, but it turned out that, even after a large number of careful like-for-like measurements sequences at various times, there was no measurable difference, not within the large experimental noise. (I have checked that the modems are indeed using G.992.3, btw.; they are. The modems are still set the same way now: ‘ADSL2’-only.)
So for me, the result was: if ‘ADSL2 only’ modem settings give any performance benefit (or the reverse!), I couldn’t prove it.
To justify enabling ADSL2+ for me would be bit-loading approaching the highest G.992.3-supported tones, ie approaching tone 255 or higher.
If you’re getting problems doing the same as me and Burakkucat, then I can’t understand why. But if your situation is at all comparable to ours, then you should be fine leaving your modem set to ADSL2+ or auto-select, unless it is somehow being weird about its own ADSL2+/ADSL2 config settings values.
If you can use ADSL2/G.992.3 then I would say it is worth trying the ADSL2 modem setting as there’s definitely no harm in it and it might even be better as Burakkucat originally suspected.
