Hi, I'm Nergal, good to meetcha!   
So since downloading PRO, I've had problems connecting unfortunately! This appears to be completely on my end as I know no-one else that's been getting this problem in the same way. 
Nature of the problem 
Connecting to the Gold Server which I play on (Silver Server has been tested and encounters the same problem) causes me to get a "Connecting to server..." message for about 5-10 seconds, then "Can not connect to server" after that. 
It usually takes about 5-10 minutes before I am able to log on, receiving the prompt "Logging in...". 
The access condition to the server seems to be random with respect to time, as I cannot identify what allows me into the server.   
Solutions I have tried / Notes 
- Checked for previous threads, one member had an issue due to country, as he was connecting from the UAE, I am residing in the UK. 
- I have redownloaded the client fully, same issues. 
- Have disabled realtime protection with my antivirus and firewall, Windows Defender. 
- Have added the PRO client application to the list of allowed apps through Windows Defender Firewall. 
- Have run the PRO client application through administrator on my desktop. 
- Restarting router   
Extra Information 
- Firewall & Antivirus: Windows Defender 
- Network: Home, private network wifi - no VPN 
- Location: England, UK 
- Hardware: Acer Nitro laptop   
Any suggestions are welcome, no matter how ridiculous!   
..Well maybe not sprinkling garlic over my router, that's far beyond ridiculous.   
Many thanks! 
Nergal (Master Dan)