If you can’t start an 5250 session, you can try to change the value with ftp. Start an ftp session to the as/400, login as qsecofr (or another account with enough rights) and enter the following command :
quote rcmd call qcmdexc (‘chgsysval sysval(qautovrt) value(999)’ x’000000003700000F’)
The 37 in the second parameter is the length of the first parameter (if I counted right), change this after filling in the 999 with the right value to the new length of the command.
In this way you can start almost any command to be remotely executed, if the rights are correct.
A second method, which is better in this case but not as flexible, is to go to the Client access operations navigator on the your pc. Go to your system, configuration and service (I have a dutch version, so I’m translating back), system values, devices and change the value in automatic configuration, pass-through devices.