AS seems to be working fine still for the dsl uptime, dsl uptime still works.
The modem uptime is now what is broken.
I can confirm tho that on my device the total time is not capped to 2 days. So that should work as a means to measure the modem uptime.
So...
"since link time" or "AS" both should be fine for dsl uptime (so keep that as is).
"total time", useable for modem uptime on the zyxel 3925-b10b. Before I flashed this correctly showed uptime in excess of 200 days.
Total time = 212 days 6 hours 36 min 32 sec
FEC: 176459 1601
CRC: 6451 121
ES: 62343 7273
SES: 70 1
UAS: 145 114
LOS: 3 0
LOF: 17 0
LOM: 0 0
Retr: 3
also the good old "uptime" command seems valid as well.
# uptime
18:35:41 up 18:35, load average: 0.29, 0.29, 0.31