There may be something spurious going on with certbot renew in the past 24 hours or so. I had a similar failure (1st failure in 5 years and 20 or so renewals). It gave the same "likely firewall problem" and I dropped my firewall and ran certbot renew again and all succeeded -- but I have my doubts if it was really firewall related.
My similar question is 1 of 15 domains failed certbot renew of cert...