Extending Arlo base range with WiFI Range Extender EX7300

[Desmodave]

I have an AC1750 dual band router that's been working very well, but it's a couple of years old.  I first set up the EX2700 range extender and it's worked OK, but still didn't have the connection bars I wanted.  The router is at one end of the house and the carport/garage cams are at the other, about 100 ft, not that far.
So I first bought the EX7500 (2 of them), but since they didn't have an ethernet port (why not?) I purchased the EX7300 thinking that two bonded channels would be much better than a half/speed channel with the Ex2700.  Well, it's about the same, bandwidth has improved, but strength of signal is still at one bar.  One thing that I was told by support was to not use the _ext as the second name of the range extender.  So now I've got a true mesh network with one name running on three bonded channels on the EX7500 and two channels on the EX7300.  In some cases I've got 6 or more channels available.  On Comcast/Xfinity my max speed at the router is 200 mbps and now I'm pushing 800mbps throughout the house, so the increase in overall speed is spectacular, especially for such an old router.
I've confirmed that the Arlo Base is connected to the EX7300 because I can see the IP address and it's shown as an attached device.  What doesn't show up is the link light for the ethernet port (this did show up as a linked device on the EX2700, but not with the EX7300).  My assumption was that now that I've centrally located the Arlo base, punched up the bandwidth that I'd at least see some sort of improvement in the signal strength, but not so.  At least that's what the Arlo buyers guide states when trying to extend the range of the Arlo base.  So now that I've spent another $500 to get a couple of more bars of signal, I haven't improved anything.  So what part of this equation need help?

[jguerdat]

First thing that pops to mind is the distance and house consrtuction. If you moved the base closer to the cameras but no real improvement with the signal, something is interfering with the base-camera connection. Stucco houses, for instance, frequently use a wire mesh that holds the stucco firmly but acts as a Faraday cage to the signal. Mounting the cameras on a metallic surface may also be an issue.

As for the extender LED not showing the base as connected, perhaps anything less than a gigabit connection doesn't get that indicator? Usually it' green for gigabit and amber for less. The base has a 100Mbps connection.

[Desmodave]

Yes, something interfering, but it's not wire mesh in the building.  In the Pacific Northwest stucco houses aren't built because of our cliimate.  Most houses are conventional stick framed with cedar siding or hardy plank, so that's probably not the issue.  I have a clear line of sight from where the base is located to most of the cams.

I think I'll move the base out into the garage and see what happens there, because I'll only be 20 or 30 feet away from the cameras.  As for the ethernet connection, any connectivity should show up, it's just like any other router or hard-wired ethernet connection when you plug it in. 
Thanks for your sugguestions.