i've performed the following to switch to the non-ct version of the firmware for my Turris Omnia:
# opkg update
# opkg remove ath10k-firmware-qca988x-ct kmod-ath10k-ct && opkg install ath10k-firmware-qca988x kmod-ath10k
# reboot
so far everything is working fine. i'll check back in a few days to report if the stability has improved.