MediaTek Helio X20 (MT6797)

My apologies if I am in the wrong forum, which if I am would you please point me in the right direction.

I’ve just purchased a MediaTek Helio X20 (MT6797) tablet from a dealer on eBay.
It is advertised by the dealer as a “dual sim” device, is it? The limited manual enclosed doesn’t help and I can’t physically see where they can be inserted. There is a pinhole, similar to that on my S9+ phone but it is next to the Volume control and appears to do nothing.

Wi-Fi - my Netgear router supplies both 2 and 5 GHz bands. All my other android devices find the 5 GHz band without problem. The Helio X20 only finds the 2GHz band but the Wi-Fi spec on the Helio X20 page suggests it should be able to. What am I missing?

Any help appreciated, Peter.

Contact your hardware vendor. This forum is for single board computers, which has nothing to do with your tablet.

Thanks. The dealer I purchased it from is being of limited help so I thought I’d
try get some answers here. I wrongly assumed as the header on this page says
MediaTek Helio X20 (MT6797) product support MediaTek-X20" this was the place
to come.
Is this forum connected to MediaTek , if yes, is there another forum dealing with
support for their tablets, It boots up with the MediaTek and not a third party logo.
Or are the tablets manufactured by another company using this motherboard? If the
latter do you know who produces them so that I can contact their support.
Thanks, Peter