I have a couple of HomeHub 5's running Openwrt bought off ebay.
One of them I've noticed doesn't always seem to init the DSL modem when it's powercycled / Rebooted.
Tried loading a newer DSL firmware but still same issue, last time it happened I ssh'd in and executed a /etc/init.d/dsl_control restart which bought it to life, doesn't seem to matter if I change the DSL settings or not.
Modem state ends up in L3 - No Power / Line State: DOWN [0x200: silent]
Not sure if the other one has the same problem as haven't had it long enough yet to find out (It worked when I plugged it in).
Once the modem decides to work it seems stable, it's just getting it to start in the first place that seems a bit problematic, not sure if it's a hardware issue or just a timing issue so was wondering if anyone else had seen this problem.
The troublesome router was on 19.07.4 but I recently upgraded it to 19.07.5
Interesting one of the DSL firmware's that doesn't sync at all on one of the homehub's works fine on the other one, Both lines connect to the same DSLAM and have the same VDSL profile so that's a little odd. Wonder if it's a hardware revision or maybe one of the modems is a bit iffy.