Are the echo in between the main router and an access point? I solved my "echo is unable to connect to the Internet" and the blue circle loop you are describing by creating a guest network with Lan access on both my EA6900 with merlin and my access point extender with dd wrt, same settings, and also put the dots in static ip with Google dns.
Also enable the roaming assistant (which basically drops the client at certain power level to allow to connect to the adjacent access point.
If this makes sense for you, please try it.
Echo response time improved too after this.
Hope this helps
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