MWAN-3 on AR-150 v2.25

I’m sorry if the question has already been discussed.
Dear gurus, please give advice.
I have Gl.inet AR-150 with the latest firmware 2.25. The router is used to connect to the Internet. The main channel – LAN DHCP. As a backup – 3G USB modem.
I am trying to adjust MWAN to switch between channels. I did everything according to the instructions found on the Internet.
If the LAN connection physically falls – router switches to 3G. If it disappears ping (on a pre-specified IP, for example, In MWAN Lan connection goes to the drop, 3G – up, but the Internet does not appear until physically disconnect the LAN cable. It then can be connected back to the Internet will remain on 3G, up to the time the ping recovery on LAN.
After several hours of experimental settings concluded that the normal Internet connection via 3G interferes with easy web interface Gl.Inet. If there is a physical connection on the LAN bypass MWAN he tries to access the Internet via the LAN. Perhaps for this kind of script responds to a simplified web interface.
Who faced with similar and what will be your advice?
Thank you in advance!

It is a bug of MWAN3.

Need to debug it.