Poor 5GHz wifi performance on Netgear 6260

I have installed the OpenWRT 19.07 snapshot. A stable release is listed for my hardware but the link is a 404. The 2.4G Miritek wifi radio works brilliantly, whilst the 5ghz radio is shown as "Generic" and the performance is just awful. Literally have to be within a metre of the device to get any kind of signal on ac wifi. Does anyone have any ideas regarding this? I would like to be using a stable release firmware but cant find one, despite it being listed as compatible hardware . Could I use the image for the R6220?

Any ideas?

mt7615 has horrible support in the 19.07 branch. Please use a snapshot from the master branch.

Thanks for this. By the "master branch", do you mean 18.06 ? I new to OpenWRT and I'm finding the versioning a bit confusing.

They don't have a version number yet, since they are development snapshots. Download links here:

https://downloads.openwrt.org/snapshots/targets/

'Master' is the default branch of a git tree (used as a synonym for 'development'). What used to be 'trunk' on SVN, which OpenWrt used previously. Anything with YY.MM numbering is a stable version.

Thanks for the notice, I have changed the dataentry back to snapshot, since 19.07 images do not exist.