I have been using OpenWrt on various Lantiq devices for quite some time now. One thing I often had problems with was the stability of the xDSL connection.
Debugging these problems turned out to be difficult, since the providers I used so far usually refused to give free support when using a modem they didn't provide. Another problem was the absence of useful error messages when a xDSL disconnect happened, which is most probably because something in the modem firmware went wrong.
After having my line checked by a technician, which showed no problems, I began to test various firmware files from http://xdarklight.github.io/lantiq-xdsl-firmware-info/ and still didn't have success.
After finding another vrx200 firmware file on the web and using that, I was quite delighted to find my VDSL line completely stable for about 20 days now.
Finding the correct firmware file probably depends on a lot of different variables (device, OpenWrt version, line mode, annex, DSLAM manufacturer, etc.) and I fear it will be nearly impossible to cover all cases.
However it would be nice to make it easier to use OpenWrt devices as xDSL modems. There are a few reports by people on the forum that had a stable xDSL connection after installing a specific firmware, but these reports are buried deep down in various different threads. My proposal would be to collect the "I have found my perfect firmware" stories in one thread, so that other people have a starting point and at least have a better chance to find a suitable firmware sooner.
So, if you have a stable xDSL connection with OpenWrt, reply with the output of the following command:
echo; egrep '"id":' /etc/board.json | sed -nE 's/(\s*"id":\s")(.*)(",)/\2/p'; egrep 'OPENWRT_RELEASE' /etc/os-release | sed -nE 's/(OPENWRT_RELEASE=")(.*)(")/\2/p'; /etc/init.d/dsl_control status | egrep 'ATU-C Vendor ID:|Firmware Version:|Line Mode:|Annex:|Line Uptime:'