WZR-9000DHP LAN vs WiFi

[dkriddle]

I ask for your patience in advance. Maybe this question is not logical, but...

I use a WZR-9000DHP Air Station Buffalo router that has both 2.4 and 5 Ghz SSIDs for WiFi. They work well. 
When using LAN only with WiFi off, I connect only with 2.4 GHz and can find no way to include 5 Ghz.  The 2.4 Ghz connection is much slower than the 5 Ghz connection.

How can I make the LAN use the  5Ghz connection?

My computer is MSI GS60 2PC(Ghost).  OS is Windows 10 Home (Anniversary Edition)
I am in Tokyo, Japan - my ISP is Asahi.net using NTT FLTS connection

[davo]

"When using LAN only with WiFi off, I connect only with 2.4 GHz and can find no way to include 5 Ghz"

This statement makes no sense.

[dkriddle]

Sorry.  I expressed myself badly. 
When using LAN only with WiFi off, it connects only with 2.4 GHz and I can find no way to include 5 Ghz.  The LAN connection is much slower than the 5 Ghz WiFi connection.
Perhaps this is an issue with my LAN connection and is unrelated to my Router?

[dkriddle]

I changed the LAN cables from category 5 to category 6 and this solved the problem.