RHB now cannot connect with qb why?

Try opening your QBO account on any private/incognito browser.

I appreciate you taking the time to post your concern here in the Community.

Before anything else, did you encounter any error when trying to connect your bank to QuickBooks Online (QBO)? If so, can you tell us what type of error it is? It could help us determine the type of issue and provide you with a timely solution.

On the other hand, if you didn't encounter any error when linking your bank, it could have something to do with the browser. QBO can occasionally be poorly configured due to overloaded site data. To ensure that you'll get to connect your bank account to QuickBooks, I recommend following what @Fiat Lux - ASIA has suggested. 

Here are some of the supported browsers and how to activate their private window:
 

• Google Chrome and Microsoft Edge: Ctrl + Shift + N
• Mozilla Firefox: Ctrl + Shift +P
• Safari: Command + Option + P

For the time being, I recommend manually uploading transactions in QuickBooks so you could get to match and categorise them with the existing entries in QBO.

Moreover, I'll also share this article that can serve as you reference if you want to learn how to use bank rules to automatically categorise transactions from your bank: Set up bank rules to categorise online banking transactions in QuickBooks Online.

I'm looking forward to having your bank connected to QuickBooks. Feel free to leave a reply if you require further assistance with linking banks in QuickBooks. The Community team always has your back. Have a good one.