My custom build, from official repo and stable 19.07.4 sources.
Link: https://drive.google.com/file/d/1O8CI3suUdxcBbCdRLxSbulAXr0UN9BnJ/view?usp=sharing
This was the way I took to build it on a 16 core machine, it needs a lot of free space (30 GB at least).
#!/bin/sh
apt-get update
apt-get install -y build-essential libncurses5-dev gawk git libssl-dev gettext zlib1g-dev swig unzip time rsync python3 python3-setuptools
#
mkdir -p "/root/build"
cd "/root/build"
git clone https://git.openwrt.org/openwrt/openwrt.git
cd "/root/build/openwrt"
git checkout v19.07.4
./scripts/feeds update -a
./scripts/feeds install -a
make menuconfig
#
# Selections
## Target System (Atheros ATH79 (DTS))
## Subtarget (Generic)
## Target Profile (TP-Link Archer C7 v5)
## Firmware
### <*> ath10k-firmware-qca988x
### < > ath10k-firmware-qca988x-ct
## Kernel modules
### Filesystems
#### <*> kmod-fs-ext4
#### <*> kmod-fs-msdos
### Network support
#### <*> kmod-batman-adv
### USB Support
#### <*> kmod-usb-storage
### Wireless drivers
#### <*> kmod-ath10k
#### < > kmod-ath10k-ct
## LuCI
### Collections
#### <*> luci
## Network
### VPN
#### <*> openvpn-openssl
### <*> batctl-full
### < > wpad-basic
### <*> wpad-mesh-openssl
##
#
# cp "/root/build/openwrt/.config" "/root/build/.lastconfig"
# cp "/root/build/.lastconfig" "/root/build/openwrt/.config"
#
export FORCE_UNSAFE_CONFIGURE=1
make -j 16
# make -j1 V=s
#
# Output
## /root/build/openwrt/build_dir/target-mips_24kc_musl/linux-ath79_generic/tmp
#
exit 0