I am not an expert when it comes to computers but I get by, just about.

I changed broadband provider 3 weeks ago and now have a dynamic ip address but I've not seen it change yet.

I setup port forwarding in my router and everything has been working perfectly.  This morning everything was fine but this afternoon DHT disappeared from the bottom of the screen and I don't why.

DHT is 'Online' and running.

Could DHT be corrupted?  Can I delete DHT in %appdata%, could that be the problem?  If I try deleting DHT what exactly should I delete?  
Will this affect anything with old and current downloads?

Thanks

I am normally connected to the internet by ethernet.
I disconnected ethernet, now connected by wifi and I noticed DHT changed to 'Online - port blocked'.
Connected back to ethernet and DHT changes back to 'Online'.

On Firefox I did try an extension: SetupVPN Lifetime Free VPN but then uninstalled it.
Could that have caused a problem?

So the port is blocked but only on wifi, not by ethernet but even with ethernet something is not right because I don't see DHT nodes at the bottom of the screen any more.

My local IPV4 number is the same (the one used for port forwarding in my router), it has not changed but my public ip address has changed.
Could this be causing the problem?

I don't completely understand everything about ip addresses.

Should I try setting up separate port forwarding rules for TCP and UDP, using different ports?

Just to be clear, if I did this, I would have to set this up, in the router and create rules within Windows Defender Firewall?

I am able to upload and download but I want to know why I suddenly had an issue with DHT, where DHT is showing as 'Online' when connected by ethernet but 'Online - port blocked' when using wifi?

>I am able to upload and download but I want to know why I suddenly had an issue with DHT, where DHT is showing as 'Online' when connected by ethernet but 'Online - port blocked' when using wifi?

Because your ethernet uses different physical device as your WiFi. They have different MAC addresses and so they have different IP-addresses too. If you have done port forwarding to let's say IP 192.168.1.5 and that is what your ethernet uses that is why it works. However when you switch to WiFi you get different ip address, such as 192.168.1.10 and therefore the DHT will show port blocked.

Where do you see DHT “in the bottom of the screen” in Tixati?

Browser extensions obviously don't affect other programs. they only switch proxy in the browser.

The node count of the DHT used to be displayed at the bottom of the screen, but has been removed in the newest version.

Thanks for the replies.
Why was the node count removed from the bottom of the screen? I found it useful, it let me know if there was a problem with DHT.  Perhaps there is no problem with DHT when connected by ethernet but because I can't see the node count I won't know.
Can it be seen some other way?

If you go to the Node Table tab on the DHT tab you will see the node counts.
And if the DHT icon is red instead of blue, thats how you tell if you have a problem.