Thank you @MikeMcQ and @rg305 for the feedback.
I only mentioned "self-signed" as if to bypass the current issue of the cert being invalid by forcing the app to accept the cert. Unfortunately, there is no option for that available for either of the apps that I am using to access the site which is the URL to the server on my NAS. Both of these apps require SSL to be used to access the RSS server that I have self-hosted.
Why I initially said it expired is because of how I'm seeing it based on the following screenshot:
Now I don't know how to address this based on what you have provided me. That it is a "leaf" I don't understand, and how to get the whole chain to be sent is something that I have tried to research and find out. All that I did to install the certificate was essentially push a button on my QNAP NAS to get it installed. I've also included my logs below the screenshot.
e[1;32m11/04/21 00:53:00: ../common/src/log.c: 146: qnap_log_chk_file_size(): log restart e[0m
e[1;32m11/04/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/04/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=89e[0m
e[1;32m11/05/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/05/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=88e[0m
e[1;32m11/06/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/06/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=87e[0m
e[1;32m11/07/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/07/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=86e[0m
e[1;32m11/08/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/08/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:43:15: ssl_agent.c: 885: main():start cmd=get_statuse[0m
e[1;30m11/08/21 03:43:15: ssl_agent.c: 896: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:43:15: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;32m11/08/21 03:43:16: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;30m11/08/21 03:43:16: ssl_agent.c: 909: main():response: { "result": { "cname": "pacmannas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "firmware_verison": "4.3.6" }, "status_code": -3000, "message": "get_certificate_info failed" }e[0m
e[1;30m11/08/21 03:43:16: letsencrypt_agent.c: 555: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:43:16: letsencrypt_agent.c: 225: execute_command():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:43:16: letsencrypt_agent.c: 257: execute_command():certificate_info status_code=0e[0m
e[1;30m11/08/21 03:43:16: letsencrypt_agent.c: 568: main():response: { "result": { "certificate_domain_name": "PacManNas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "web_site_domain": "myqnapcloud.com", "qid_primary_email": "ahaghgoo@ucla.edu", "authority": "Let's Encrypt", "applied_on_device_start_datetime": "2021\/11\/02", "applied_on_device_end_datetime": "2022\/01\/31", "is_auto_renew": 1 }, "status_code": 0, "message": "normal" }e[0m
e[1;32m11/08/21 03:43:21: ssl_agent.c: 885: main():start cmd=get_statuse[0m
e[1;30m11/08/21 03:43:21: ssl_agent.c: 896: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:43:21: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;32m11/08/21 03:43:21: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;30m11/08/21 03:43:21: ssl_agent.c: 909: main():response: { "result": { "cname": "pacmannas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "firmware_verison": "4.3.6" }, "status_code": -3000, "message": "get_certificate_info failed" }e[0m
e[1;30m11/08/21 03:43:21: letsencrypt_agent.c: 555: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:43:22: letsencrypt_agent.c: 225: execute_command():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:43:22: letsencrypt_agent.c: 257: execute_command():certificate_info status_code=0e[0m
e[1;30m11/08/21 03:43:22: letsencrypt_agent.c: 568: main():response: { "result": { "certificate_domain_name": "PacManNas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "web_site_domain": "myqnapcloud.com", "qid_primary_email": "ahaghgoo@ucla.edu", "authority": "Let's Encrypt", "applied_on_device_start_datetime": "2021\/11\/02", "applied_on_device_end_datetime": "2022\/01\/31", "is_auto_renew": 1 }, "status_code": 0, "message": "normal" }e[0m
e[1;32m11/08/21 03:43:45: ssl_agent.c: 885: main():start cmd=get_statuse[0m
e[1;30m11/08/21 03:43:45: ssl_agent.c: 896: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:43:45: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;32m11/08/21 03:43:45: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;30m11/08/21 03:43:45: ssl_agent.c: 909: main():response: { "result": { "cname": "pacmannas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "firmware_verison": "4.3.6" }, "status_code": -3000, "message": "get_certificate_info failed" }e[0m
e[1;30m11/08/21 03:43:45: letsencrypt_agent.c: 555: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:43:45: letsencrypt_agent.c: 225: execute_command():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:43:45: letsencrypt_agent.c: 257: execute_command():certificate_info status_code=0e[0m
e[1;30m11/08/21 03:43:45: letsencrypt_agent.c: 568: main():response: { "result": { "certificate_domain_name": "PacManNas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "web_site_domain": "myqnapcloud.com", "qid_primary_email": "ahaghgoo@ucla.edu", "authority": "Let's Encrypt", "applied_on_device_start_datetime": "2021\/11\/02", "applied_on_device_end_datetime": "2022\/01\/31", "is_auto_renew": 1 }, "status_code": 0, "message": "normal" }e[0m
e[1;32m11/08/21 03:44:42: ssl_agent.c: 885: main():start cmd=get_statuse[0m
e[1;30m11/08/21 03:44:42: ssl_agent.c: 896: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:44:42: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;32m11/08/21 03:44:43: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;30m11/08/21 03:44:43: ssl_agent.c: 909: main():response: { "result": { "cname": "pacmannas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "firmware_verison": "4.3.6" }, "status_code": -3000, "message": "get_certificate_info failed" }e[0m
e[1;30m11/08/21 03:44:43: letsencrypt_agent.c: 555: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:44:43: letsencrypt_agent.c: 225: execute_command():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:44:43: letsencrypt_agent.c: 257: execute_command():certificate_info status_code=0e[0m
e[1;30m11/08/21 03:44:43: letsencrypt_agent.c: 568: main():response: { "result": { "certificate_domain_name": "PacManNas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "web_site_domain": "myqnapcloud.com", "qid_primary_email": "ahaghgoo@ucla.edu", "authority": "Let's Encrypt", "applied_on_device_start_datetime": "2021\/11\/02", "applied_on_device_end_datetime": "2022\/01\/31", "is_auto_renew": 1 }, "status_code": 0, "message": "normal" }e[0m
e[1;32m11/08/21 03:45:00: ssl_agent.c: 885: main():start cmd=get_statuse[0m
e[1;30m11/08/21 03:45:00: ssl_agent.c: 896: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:45:00: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;32m11/08/21 03:45:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;30m11/08/21 03:45:00: ssl_agent.c: 909: main():response: { "result": { "cname": "pacmannas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "firmware_verison": "4.3.6" }, "status_code": -3000, "message": "get_certificate_info failed" }e[0m
e[1;30m11/08/21 03:45:00: letsencrypt_agent.c: 555: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:45:00: letsencrypt_agent.c: 225: execute_command():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:45:00: letsencrypt_agent.c: 257: execute_command():certificate_info status_code=0e[0m
e[1;30m11/08/21 03:45:00: letsencrypt_agent.c: 568: main():response: { "result": { "certificate_domain_name": "PacManNas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "web_site_domain": "myqnapcloud.com", "qid_primary_email": "ahaghgoo@ucla.edu", "authority": "Let's Encrypt", "applied_on_device_start_datetime": "2021\/11\/02", "applied_on_device_end_datetime": "2022\/01\/31", "is_auto_renew": 1 }, "status_code": 0, "message": "normal" }e[0m
e[1;32m11/08/21 03:45:21: ssl_agent.c: 885: main():start cmd=check_can_request_certe[0m
e[1;30m11/08/21 03:45:21: ssl_agent.c: 896: main():cmd: check_can_request_certe[0m
e[1;32m11/08/21 03:45:21: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;35m11/08/21 03:45:21: ../common/src/cert_utils.c: 534: check_can_request_cert():check_can_request_cert request_count=0e[0m
e[1;32m11/08/21 03:45:21: ssl_agent.c: 683: execute_command():check_can_request_cert status_code=0e[0m
e[1;30m11/08/21 03:45:21: ssl_agent.c: 909: main():response: { "result": { "can_request_cert": 1 }, "status_code": 0, "message": "" }e[0m
e[1;32m11/08/21 03:46:15: ssl_agent.c: 885: main():start cmd=get_statuse[0m
e[1;30m11/08/21 03:46:15: ssl_agent.c: 896: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:46:15: ssl_agent.c: 507: execute_command():device_name=PacManNas api_endpoint=core2.api.myqnapcloud.com, portal_endpoint=www.myqnapcloud.come[0m
e[1;32m11/08/21 03:46:15: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;30m11/08/21 03:46:15: ssl_agent.c: 909: main():response: { "result": { "cname": "pacmannas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "firmware_verison": "4.3.6" }, "status_code": -3000, "message": "get_certificate_info failed" }e[0m
e[1;30m11/08/21 03:46:16: letsencrypt_agent.c: 555: main():cmd: get_statuse[0m
e[1;32m11/08/21 03:46:16: letsencrypt_agent.c: 225: execute_command():certificate remaining_days=85e[0m
e[1;32m11/08/21 03:46:16: letsencrypt_agent.c: 257: execute_command():certificate_info status_code=0e[0m
e[1;30m11/08/21 03:46:16: letsencrypt_agent.c: 568: main():response: { "result": { "certificate_domain_name": "PacManNas.myqnapcloud.com", "api_endpoint": "core2.api.myqnapcloud.com", "portal_endpoint": "www.myqnapcloud.com", "web_site_domain": "myqnapcloud.com", "qid_primary_email": "ahaghgoo@ucla.edu", "authority": "Let's Encrypt", "applied_on_device_start_datetime": "2021\/11\/02", "applied_on_device_end_datetime": "2022\/01\/31", "is_auto_renew": 1 }, "status_code": 0, "message": "normal" }e[0m
e[1;32m11/09/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/09/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=84e[0m
e[1;32m11/10/21 00:53:00: ../common/src/cert_utils.c: 553: check_is_letsencrypt_cert():this is letsencrypt certificatee[0m
e[1;32m11/10/21 00:53:00: ssl_cli.c: 324: main():certificate remaining_days=83e[0m
If you or anyone else has further feedback, I'd greatly appreciate it!!