As noted above, by both phil and mikey, you are using the worst pool possible for asics. I'd personally go with viabtc or slushpool.
Mikey also gave you good options for custom firmware. I prefer asic.to since I've been using them for quite a few years, but others are good options as well.
As for last board, I am not sure if you were overclocking it too much or cooling was insufficient but that does look like dead or dying hashboard. You could try changing positions of hashboards to see if that helps and also visually inspecting the problematic hashboard to see if there are any fallen heatsinks but those might not help.
On newer antminers (like X17) it was useful to try rotating miner by 90 degree (putting it on the side) as possible temporary solution but that might not work in your case, worth a try tho.
I wanted to recommend you something more as well but I forgot now, will edit this message when I remember.