Problem using Devolo plugs on 5Ghz

[#1]

Thanks for any advice on this one..  I am trying to get my smart TV to connect to my Devolo network extension plug on 5Ghz but the plug is only offering me 2.4Ghz wifi.  I have even turned off my 2.4Ghz on my router and only left on my 5Ghz wifi and re-synched the plugs but they seem immune to being forced to synch and adopt 5Ghz and remain on 2.4Ghz.  Any help?  Thanks,

[#2]

Maybe the plugs are 2.4GHz only?

[#3]

Model number would be helpful.

Some units will not use the 5GHz band and others will not use both bands together. If you have one of these and a mobile is connecting at 2.4Ghz nothing is going to connect at 5Ghz.