A support discussion says to disable IPv6. Another says it is essential. Before changing a working router, identify the problem you are trying to solve and which part of the connection is involved.
Two paths can coexist
A network may provide both IPv4 and IPv6. Devices and services can use them differently, so a failure affecting one path may not affect the other in the same way. Internet Society’s deployment material explains the transition and the need to understand both protocols.
The presence of an IPv6 address is not, by itself, evidence that your files or router administration page are publicly accessible.
Check the security policy on both
Do not assume that rules written for IPv4 automatically describe IPv6 behaviour. Check the router’s firewall documentation and default handling of unsolicited incoming connections for both. Keep device firewalls and software updates in the picture too.
Avoid opening services merely to test whether an address is reachable. Use supported diagnostics and ask your provider or administrator when the network is managed by someone else.
Troubleshoot with a reversible comparison
Record the symptom, affected device and service before changing anything. If support recommends a temporary protocol change, save the original setting, change one variable and compare the same task. Restore the setting afterwards unless you have a documented reason to keep the change. A workaround may identify a useful lead without resolving the underlying router, provider or service issue.