When I connect to RB450GX4 with winbox4, the prompt in the title of this post appears. When I connect with winbox3, the uptime of winbox3 does not change or suddenly becomes very large. It feels like it is stuck. When I ping the ip of rb450gx4, the packet loss is very serious. Is this a hardware problem? I have installed different versions using netinstall. The current version is 6.45.6

ping from where?, try to isolate the issue by changing the cable first and make a basic config before you jump to conclusion that this is a hardware issues

I tried elimination, changed the network cable, and tried all ports, but the packet loss still occurred.

try to moved to other ports just for troubleshooting or update to latest v6 LTS release, normally MT hardware has long life i'm still not convince it's a hardware issue and also paste your whole config here