I have a brand new A41 with nothing installed on it (fresh factory reset, did not allow any app installs on start up). I have a Virgin SIM I have confirmed works fine on other phones. When WiFi is turned on but not connected to a network or WiFi is turned off the SMS works fine. When I connect to any network, the phone can still send texts, but not receive them.
I should add, this is specific to Virgin, if I put an EE SIM in the phone it works fine with the WiFi connected. I also confirmed that it is not a global problem as I know someone else on Virgin with the same phone and does not have the issue.
So by trying another sim i.e ee as a process of elimination and that works as it should the phone itself points to be working as it should just not with your Virgin Sim card / account.
Have you double checked your messenger centre number.
There are settings to check in your messages app too.
Also it might be worth trying another messaging app from the Playstore as a process of elimination.
Lastly just to ensure it's not a rogue app clashing consider putting the phone in Safe Mode.
Put the phone in Safe Mode which disables your downloaded app's but let's your stock app's keep working. If the issues stop then this highlights a downloaded app as the possible issue. Come out of Safe Mode and start deleting your most recent downloaded app's one at a time until it stops. https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/
Current Phone ~
Samsung Note 20 Ultra 5G SM-N9860_256Gb SnapDragon 865+
Samsung One Ui 3.1/ Android 11.