Bricked 2 routers with self compiled 5.4 images

There's attempts to get OpenWRT to the next version based on Linux 5.4, I would like to join the club. However, I have already bricked 2 of my routers doing so, one is Archer C7 v2, and the other one is D-Link DIR-860L b1.

The later one is quite easy to recover, Archer C7 v2, on the other hand, failed tftp recovery and I am struggling the next step to regain control.

My question is, what is the best way to try non product firmware like that? I was using 'sysupgrade -v ' with an upgrade package, apparently is not a good idea.

I'd like your advice on that.

If someone has experience of un-brick Archer C7 v2, I'd like to get sharing from you. Thanks in advance.

5.4 introduces DSA if I'm not mistaken. You should use always use -n with sysupgrade if all you're doing is testing.

I broke my DIR-878 as well with the ramips 5.4 PR, and I'll be trying my DIR-860L as well. Both allow easy recovery through the u-boot web interface, luckily.

Not by default for all targets.

E.g. with ipq806x the same network config works ok with 4.19 and 5.4

What do you mean by "with an upgrade package"???
Generally, using opkg to mass-upgrade packages is a bad idea (if you meant that).

With new kernel versions, ideally you should test minimal images first. Just the basic functionality and maybe LuCI. Without any extra packages, and definitely no automatic package upgrading.

That sounds strange, as typically the TFTP recovery is handled by the originall bootloader (u-boot, ...) and that bootlader is not touched by OpenWrt image.