@Mizta_Banana Try another ethernet cable of Cat 5e or above. Sometimes a loose contact can cause this effect.

@Uk_pete_2000 You can try the following: Delete all the RE315 from NX200 WebGUI Easymesh network: Reset all the the RE315 by pressing the reset button for about 10 seconds. Start adding RE315 one by...

@Leh_Pics Latest FW version for v2 is TL-MR3420_V2_150319 - here. It seems that the USB port on this modem router supports only an LTE USB modem.

@jolly247 Disable Smart Connect feature in wireless settings and you should be able to change wireless channels.

@MICHALV If you forgot your RE administrative password you have to reset it to factiry defaults and reconfigure from scratch. By the way,. your RE firmware is outdated - it's suggested to upgrade it...

@azzoug Check this FAQ - Q6.