Extroot and connect the E8372

I want to set up exroot and connect the E8372 modem.
My router is MR3020 v1, Openwrt 18.04.9 builboot. I connected the hub with external power and set up exroot. But after connecting, the exroot settings flies, dsmesg shows that the hub or router is cyclically reconnecting. what could be my problem? Please help a newbie.

Does the same happen when you use an externally powered USB hub?

are you sharing the uSD card through the E8372 ?

No, only when connect modem E8372.

No, my hub includes sd card reader. I don't tried modem's sd card reader, modem watchcat is restarting modem if connection is lost. Because of this, I can lose exroot