after updating glibc6 no incoming and outgoing calls possible

RHEL 7.9 running Qemu 1.5.3, virtual machine running RHEL7.9 in ZVOL (ZFS) with Asterisk 14.7.7 and FreePBX 15.0.17.24

Bug: After the last update of RHEL7 in virtual machine, FreePBX always gives the message beep&im-sorry&your&simul-call-limit-reached&goodby when trying to make an outgoing call (for internal and external calls).Incoming external calls are terminated immediately without message: HangupCause: Normal Clearing..X-Asterisk-HangupCauseCode: 16

The modules of FreePBX are automatically kept up to date. After listing the updated RHEL7 modules, the virtual machine with FreePBX was restored to the state before the OS update and worked without problems. In order to find out the problematic OS update, first the highest causer probability was assigned to the glibc modules. After updating only to glibc-2.17-322.el7_9.x86_64, glibc-common-2.17-322.el7_9.x86_64, glibc-devel-2.17-322.el7_9.x86_64 and glibc-headers-2.17-322.el7_9.x86_64 the above mentioned error occurred again immediately without a restart.  This should not have happened...