Two hubs - limit to devices?

I have two Anker 13 data port hubs.
The first started having problems within the warranty period, so I asked for a replacement.

Since a few of the ports still worked, I decided to keep the old one and split the devices between the two with three external hard drives that I use for backup on the old hub and the rest on the replacement hub.

Seemed to work OK, but now I cannot get either hub to recognize a card reader with an SD card or the same card in my camera plugged into the computer via the hub. I am on an iMac [El Capitan] and routinely use iPhoto to download photos.

I can look at the photos inserting the card into the card slot in the back of the computer.

Even rebooted the iMac. Same story.

At the moment, I have three ExHD on the old hub - working.
And six devices on the new hub. Four ExHD, a printer and a mouse. No problems.
Thank you

Have you tried to see if the SD card can be read without anything else plugged in? It could just be a limitation as you mentioned of the device itself. You may be best off messaging support for help as I’m not sure if many of us here has experienced the various scenarios that go in with hubs.

@AnkerTechnical @AnkerSupport

Do you get the same results with your camera or card reader plugged in directly to your iMac? (to rule out the reader being at fault or the camera and connected device combinations exceeding 8A)

No, I did not try the SD card alone because I was up and running with several external hard drives and didn’t want to unplug them all.

I have been in correspondence with Anker and they reminded me of the 8 amp limit on the hub.

However, that did not explain why the old one with only three drives connected would not read the card. Presumably defective since they had sent a replacement.

Because of that uncertainty, I removed the old hub and plugged almost everything into the replacement hub.

The last one - a 6 TB drive - did not light up and was not recognized.

Ordered a 10 port hub with 10 A capability.
Thank you

At that point, I was maxed out on slots on the iMac, too, so could only test using the card reader on the back of the iMac.

I posted a more detailed account with different things I tried on the Amazon review page for the hub, but for the life of me cannot find it. It was a comment on someone’s review.

If I plug in my external CD/DVD burner and another portable external hard drive, I will be maxed out on the hub with nothing left for cards, cameras, etc.

Ordered a 10 port one today.

Thank you