A VMG1312-B10A will probably serve you well, but I wouldn't expect any large increase in sync over the DGA4132.
1. The first firmware in the wild that supported 1508 MTU on the 1312 was from Olipro, he figured out the magic words that needed to be added to a Makefile and 1 other source file in the Zyxel supplied firmware build package. Would be really cool if he showed up here in fact, sure lots of people would have kind words. This version you linked is based on the last but one release of the stock firmware and it by all means perfectly suitable for flashing and use. All I have done is apply the same patches he has to newer versions of the firmware from Zyxel, some messing with binaries related to the dsl driver and changing the telnet version to allow multiple sessions. Olipros version has fully functional telnet and ssh, the changes I have made since are just to allow multiple concurrent telnet sessions.
2. The "
V" version of the adsl_phy.bin has been the default in all builds of the 1312 (and 8324/8924) firmware for many release versions now, the latest versions I have posted and will link again here use it.
3. I did make a firmware with the "
O" version of the adsl_phy.bin for someone to experiment with, but for them at least it offered no benefit, you are free to try it yourself and I will link it too.
My advice since people have tried the newer "
X1" adsl_phy as well as the older "
O" version is to stick to the normal "
V" one that Zyxel ship with the firmware and is the only that I have used with the latest releases of the firmwares,
unless you have a BDUK area connection with vectoring, then some improvement may be realised from the later adsl_phy.
So:
The latest 1312 images based on V16:
https://www.dropbox.com/sh/c5no9h8ckyp2i4i/AADwAR6oVbzwFjtE-bLdy81Za?dl=0The weird older adsl_phy one if you wish to experiment:
https://www.dropbox.com/sh/lijl9krbghcpc2c/AAAlzU2b8mtbZ0k2shjVJpINa?dl=0The later x1 adsl_phy - best used only if you have
vectoring:
https://www.dropbox.com/s/84uvih8rex1wyed/1312-B10A-from-zyxel-jumboframes-3925adsl_phy.bin?dl=0Hope this helps, please ask for clarification if I have been confusing.
Edit: typos