@dhilbish If command line is comfortable with you, you can do it conveniently. Downloading from here, then copy it to router via scp or winscp so on.
root@GL-AR300M:~# opkg install /tmp/minidlna_1.1.5-3_mips_24kc.ipk
Installing minidlna (1.1.5-3) to root...
Installing libexif (0.6.21-1) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libexif_0.6.21-1_mips_24kc.ipk
Installing libsqlite3 (3160000-1) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libsqlite3_3160000-1_mips_24kc.ipk
Installing libbz2 (1.0.6-2) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libbz2_1.0.6-2_mips_24kc.ipk
Installing libffmpeg-mini (3.2.2-1) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libffmpeg-mini_3.2.2-1_mips_24kc.ipk
Installing libid3tag (0.15.1b-4) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libid3tag_0.15.1b-4_mips_24kc.ipk
Installing libflac (1.3.1-3) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libflac_1.3.1-3_mips_24kc.ipk
Installing libogg (1.3.2-2) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libogg_1.3.2-2_mips_24kc.ipk
Installing libvorbis (1.3.5-1) to root...
Downloading http://www.gl-inet.com/lede/2.27/ar71xx/generic/libvorbis_1.3.5-1_mips_24kc.ipk
Configuring libogg.
Configuring libexif.
Configuring libflac.
Configuring libvorbis.
Configuring libsqlite3.
Configuring libbz2.
Configuring libffmpeg-mini.
Configuring libid3tag.
Configuring minidlna.