Wrong layout when access from outside LAN

Nextcloud version 19.0.1snap3,
Operating system and version Ubuntu 16.04.7 LTS,
PHP 7.4.9

Wrong layout, when accessing Nextcloud from outside, in LAN layout is normal. Ports forwarding to LAN is 443 and 80. Example picture: https://yadi.sk/i/IgHNtK5W80XErA

How to repair this?

Can you check the URL of all the embedded content (web developer -> network). If there is a wrong hostname that can’t be resolved, you probably need to fix the overwrite-url parameter in the config file:

Also check if there is no add-blocker app in your browser that prevents loading this content.