Wireless LHG at 80Mhz

RouterOS Wireless Networking
1

I have a PTP of LHG XL, how do I put it to work on 80Mhz AC?
I can only put in 20Mhz

2

if your LHG Model is RBLHG-5HPnD-XL its not AC and its only 802.11 a/n wireless device, so You can go max 40Mhz not 80Mhz
if your LHG Model is RBLHGG-5acD its 802.11ac wireless device so you should select 5Ghz AC mode on Band to catch 80Mhz