Migrating WordPress with HTTPs Secured by LetsEncrypt to New Server

Server
13

I guess I don't have such a combined certificate:

$ sudo letsencrypt certificates
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Found the following certs:
  Certificate Name: mydomain.net
	Domains: mydomain.net test.mydomain.net www.mydomain.net
	Expiry Date: 2017-07-01 04:01:00+00:00 (VALID: 88 days)
	Certificate Path: /etc/letsencrypt/live/mydomain.net/fullchain.pem
	Private Key Path: /etc/letsencrypt/live/mydomain.net/privkey.pem
  Certificate Name: test.mydomain.net
	Domains: testwp.mydomain.net test.mydomain.net
	Expiry Date: 2017-07-01 00:54:00+00:00 (VALID: 88 days)
	Certificate Path: /etc/letsencrypt/live/test.mydomain.net/fullchain.pem
	Private Key Path: /etc/letsencrypt/live/test.mydomain.net/privkey.pem
  Certificate Name: forum.mydomain.net
	Domains: forum.mydomain.net
	Expiry Date: 2017-07-02 20:57:00+00:00 (VALID: 89 days)
	Certificate Path: /etc/letsencrypt/live/forum.mydomain.net/fullchain.pem
	Private Key Path: /etc/letsencrypt/live/forum.mydomain.net/privkey.pem

Well, at least I've got 88 days to solve this problem...