What do you base that on - the attenuation?
That's based on what you said. The Home Hub synced higher.
The Asus has a 3dB SNRM and G.INP is active. That's as good as the line will go and the optimum DLM profile.
You can't disable Interleaving, it's handled automatically by the DLM (Dynamic Line Management system).
The line isn't actually interleaved anyway. The Asus reports any Interleaving value above 1 as "Interleaving".
The line has an Interleaving value of just 4, which is consistent with G.INP (aka retransmission).
If the line was actually interleaved the Interleaving depth would be 1500+.
Also, is there a way for me to check for any CRC errors?
CRC's are reported at the bottom of the DSL Statistics page, although I've no idea how accurate that figure is.
It used to be incorrect but they may have fixed that.
In order to view any more detailed statistics (like ES, which are much more important than CRC) you have to Telnet/SSH in to the Asus and run a series of commands.
If you had a bridge modem lying around the Asus makes an excellent router. It can basically be turned in to an Asus RT-AC68U.
That would allow the Asus to handle the authentication, wireless, routing, allowing you to continue to use the Asus app, but without the (imo) disastrous modem being used.
Some users on shorter lines like yours actually like the DSL-AC68U. It's on medium to long lines where it performs worst.
If you do choose to continue to use the Asus please ensure UPBO is always enabled.
It is the only modem I have ever come across that allows UPBO to be disabled and doing so can seriously impact the upstream speed of other users on your cabinet.
It's quite shocking that option even exists and even more shocking that it has persisted across dozens of firmwares for over half a decade.