Since 18.06, OpenWrt no longer provide image for tl-wr703n because of default 4m flash is not enough.
If you want to use latest OpenWrt on your modified tl-wr703n.
You have to build it on your own.

Precompiled

Download my precompiled OpenWrt image for tl-wr703n from here:
https://downloads.hackinggate.com

TL-WR703N-OpenWrt-19.07.0.png TL-WR703N-OpenWrt-16m.png

Prepare to Build

Update: If you want to build the latest version 19.07.2. Just replace the version number in my tutorial.

Please read Install build system and Quick Image Building Guide.

Make sure all dependencies are installed.

Clone source code and install feeds

git clone https://github.com/openwrt/openwrt.git
cd openwrt
git checkout v19.07.0
./scripts/feeds update -a
./scripts/feeds install -a

This will build the latest Snapshot. If you want stable release. git checkout [TAG].

Make sure there’s no dependency error.

Make sure there’s enougth RAM or Swap.

Add tl-wr703n-v1 defination

After I took some look at the source code.
Edit target/linux/ar71xx/image/generic-tp-link.mk.
Add the tl-wr703n-v1 define above tl-wr710n-v1. Note the TPLINK_HWID is different with tl-wr710n.
If you have modified flash. For me it’s 16m.

define Device/tl-wr703n-v1
  $(Device/tplink-16mlzma)
  DEVICE_TITLE := TP-LINK TL-WR703N v1
  DEVICE_PACKAGES := kmod-usb-core kmod-usb2
  BOARDNAME := TL-WR703N
  DEVICE_PROFILE := TLWR703
  TPLINK_HWID := 0x07030101
  CONSOLE := ttyATH0,115200
  IMAGE/factory.bin := append-rootfs | mktplinkfw factory -C US
endef
TARGET_DEVICES += tl-wr703n-v1

Configure Build

Use this config.seed (modify link if you are building for stable release)

wget https://downloads.openwrt.org/releases/19.07.0/targets/ar71xx/generic/config.buildinfo -O config.buildinfo
rm -rf .config*
mv config.buildinfo .config

Add the following two lines to .config

CONFIG_TARGET_DEVICE_ar71xx_generic_DEVICE_tl-wr703n-v1=y
CONFIG_TARGET_DEVICE_PACKAGES_ar71xx_generic_DEVICE_tl-wr703n-v1=""

You should see TP-LINK TLWR703N v1 appeared in Target Devices.

make defconfig
make menuconfig

Start to Build

This will take minutes to hours.

nohup time make -j4 V=s &

  -j [jobs], --jobs[=jobs]
       Specifies the number of jobs (commands) to run simultaneously.
       If there is more than one -j option, the last one is effective.
       If the -j option is given without an argument, make will not limit the
       number of jobs that can run simultaneously.

Log file is nohup.out

View real time log via tail -f nohup.out

Troubleshooting

If you see error like this.

WARNING: Makefile 'package/feeds/luci/luci-proto-modemmanager/Makefile' has a dependency on 'modemmanager', which does not exist
WARNING: Makefile 'package/feeds/packages/meson/Makefile' has a dependency on 'python3-pkg-resources', which does not exist

Try do this.

./scripts/feeds uninstall meson luci-proto-modemmanager

And don’t forget to apply.

make defconfig

Clean the build.

make clean

If still failing, try -j1 to see real error.

make -j1 V=s

In my case, openvswitch-2.11.0 was failed to build.

./scripts/feeds uninstall openvswitch

Flash Image

Upload image to router (OpenWrt) and upgrade.

scp bin/targets/ar71xx/generic/openwrt-ar71xx-generic-tl-wr703n-v1-squashfs-sysupgrade.bin root@192.168.1.1:/tmp/
ssh root@192.168.1.1
sysupgrade -i /tmp/openwrt-ar71xx-generic-tl-wr703n-v1-squashfs-sysupgrade.bin

After install

I have some tips for you. Shell script for upgrade all packages, DNS-over-TLS, etc.
https://gist.github.com/HackingGate/b75ac856397075756ea878380c5b848c