Hi @root,
Thanks for your debugging gzip and testing that the workaround was successful.
It looks like the core of the issue is that the Armbian kernel you're using doesn't enable CONFIG_IPV6_MULTIPLE_TABLE (even though it does enable CONFIG_IP_MULTIPLE_TABLES, the IPv4 equivalent). While you don't use IPv6, so this doesn't really matter for you, others do and the ability to do policy routing with multiple routing tables is pretty much an "expected feature" of Linux these days. So it's a bit odd that it's there for v4 but not for v6. I'm guessing this is just a simple error in the default kernel config, so I've submitted this pull request for fixing it: https://github.com/armbian/build/pull/727
In any case, from your perspective, I think the workaround suggestion of my first reply is the correct way. Since you're not using v6, and not specifying a v6 interface address, it doesn't make much sense to have the v6 default gateway (::/0) in AllowedIPs or in your routes. So, with the change you made, things are now coherent and fine.
We have, in the process though, unearthed a potential problem for other Armbianers down the road, so thanks for the detailed report.
Jason
