What do you mean by poorly designed PPP stack? I'm not facing any ppp-client configuration loss cases but the thing is that my 3G modem is connected steadily but my CDMA modem is sometimes restarting in very low time period. It differs time to time but mostly 1 from 5 reboots are succesful which means CDMA is connected and is not droping connection.@jkrepinsky
Is your USB hub powered by external PSU?
Two month ago I made similar config (hub + 2 modems) and everything was OK.
I've tested two different hubs and finally worked one built using NEC chip.
Unfortunately, I don't remember what exactly chip it was.
That is the norm with any ROS versions I've seen. The ROS PPP stack is weak, poorly designed or what not, but you have nothing more to do than try to work around it. Usually a Watchdog rebooting the unit will help you deal with that issue. Sadly you have to tackle the "ppp-client configuration loss" issue as well: http://forum.mikrotik.com/viewtopic.php?f=2&t=68951.
I've asked because USB port is limited to 500mA and two modems connected to hub without external PSU overload USB port.Do you think that this home-made powering might be problem?
IMHO, MT permanently make some improvements, never mentioned in changelog.
As I wrote earlier I had problem (disconnections) with AnyDATA ADU-520L and RC10.
These disconnections never occured with RC12.
http://www.mikrotik.com/download/share/ ... .0rc12.npk
Does your CDMA modem work properly when is connected directly to PC?
I have AnyDATA ADU-895L (notice L, not H) and works fine with ROS 6.0rc12.
IMHO, one thing is missed in our considerations, even the same modem type can have different firmware version.
Maybe this is reason why for one person modem works as expected, but for other doesn't.