Strange internet connection problem with iMac

[hanser]

I had a general internet problem (on the privider side) last week which has been now resolved. For this I had to set up my rounter as new. Now internet works with every Mac, iPHone and iPad in the house except with my M1 iMac. There it works partially. I can access the internet via firefox (typing this for example), but not on Safari. Also, Mail does not connect to my mail accounts (on iPad and iPhone it works fine). Even more strange: On the Mac account of my wife on the same machine, she can NOT access the internet via Firefox (Safari and Mail do not work either). All this is the same on LAN or Wifi, no difference. If anybody here has an idea what may be the cause and how to repair it, I would be very grateful.

 

[Bigwaff]

First, shutdown and boot into Safe mode.

Start up your Mac in safe mode

Starting up your Mac in safe mode may help you diagnose problems with your Mac.

support.apple.com

Check if network issues persist. Either way, shutdown and start normally. If network issues persist, need more info. Post screenshots of your wired and wireless connection settings.

 

[BrianBaughn]

Another test would be to set up a new, test account on the M1 iMac. If everything works with that then you're down to figuring out what's configured improperly in the affected accounts.

If the new account is also problematic then there might be some setting on the router that is only affecting the M1 iMac.

 

[Fishrrman]

Something else to try:
Physically disconnect ethernet and turn off wifi (for now).
Go to the network preference setting and DELETE all existing connections.
Power off. Then reboot.
Now, connect the ethernet cable again. Turn on wifi.
Go back to network and create NEW connections for both ethernet and wifi.

(no promises, but it might help)

 

[hanser]

Thanks a lot for your suggestions. Safe mode or new account does not make a difference, so it seems to be a problem of connection/router. As soon as I have the time I will try to create new connections, but today I am away from the iMac. Would perhaps a restoring of macOS make a difference?

 

[hanser]

Something else to try:
Physically disconnect ethernet and turn off wifi (for now).
Go to the network preference setting and DELETE all existing connections.
Power off. Then reboot.
Now, connect the ethernet cable again. Turn on wifi.
Go back to network and create NEW connections for both ethernet and wifi.

(no promises, but it might help)

Thank you, that solved it! Well, it solved ethernet. I could not delete Wifi, but afterwards I looked into the details of Wifi and found an old DNS server number that I changed to the number found now in the ethernet details, and then it worked, too. Thanks again for the help!