Here I am linking two files I compiled myself with some motivation from some nice people at the OpenWRT IRC Channel.
And thanks to the modifications made to the source code by frankveltmans @ github
The linked firmware is a fairly simple version, having LuCI but only as http service and with WPAD-Wolf or Openssl precompiled (I forgot which one) but 802.11s works. I think the factory.bin file has the same things as the sysupgrade, but I’m not sure. I installed both anyway.
If you need any other packages precompiled in the firmware let me know, as all the sources and stuff are on the server anyway and it’s fairly easy to recompile.
To install you will need to follow these instructions:
https://service-provider.tp-link.com/nl/events/502/
Make sure you change the filename of squashfs-factory to M5v1_tp_recovery.bin or else the router will not take it. The sysupgrade one you can then later add through LuCI. There the name does not matter.
https://ha.lc/openwrt-ipq40xx-generic-tp-link_deco-m5-eu-v3.0-squashfs-factory.bin
https://ha.lc/openwrt-ipq40xx-generic-tp-link_deco-m5-eu-v3.0-squashfs-sysupgrade.bin
Good Luck!