Help with Asus AI Mesh

Hi, I need some advice on my Asus AIMesh set up. I've been having speed and connection issues the last few weeks and am looking for some help.
Setup is Rogers Ignite 1Gb with the white CODA router in Bridge mode feeding an Asus AC 66U. The AC 66U is then wired backhaul to another AC 66U in the basement. These 2 were set up for Asus AI Mesh. The issue is that I get major speed differences. Here's some tests I ran:
Rogers CODA modem - direct connection, I get around a 1gb/s down and 30mb/s hardwired and between 400-600Mb/s wireless on the 5G band.
With the AI Mesh set up as above, this drops way down to about 100 Mb/s hardwired into the one of the 2 Asus routers or 45-70 Mb/s wireless.

I've called Rogers and they say it's not on their end, they don't see any signal issues coming into my house. Question is what could be causing the massive slow down? Is there some setting I'm missing on the CODA modem while in bridge mode? or something with the Asus routers limiting speeds? i'm really confused.

Also, anyone seeing more Rogers dropouts now? I'm getting like 3-4 disconnects a day now where the CODA router just resets itself

Thanks for any help