Alexa not re-linking to Hubitat

I was able to link my hubitat (c5) to alexa before. However, when I changed firewall (opnsense), it stopped working. I have zenarmor and adguard. I whitelisted on both. Also, my firewall rule is to allow all traffic going out of my hubitat ip address. I even put a rule where my wan can connect to my hubitat.

So I removed echo skills on hubitat, then unlinked hubitat from alexa. When I tried to relink it again, I was able to get to oauth page, login to my hubitat. Select my hub, but I alway get the error of Unable to link account with alexa.

Also, one thing I noticed. I had C7 before, but it broke (usb power detached to the board). I can still see it on oath page, but when I go to, I don't see my C7 on registered hub.

So why am I unable to link my account? Also, can is my not-registered hub still showing in oath page? Please help. Thanks.