Hello,
On our Vigor2926 after updating the firmware to the 3.9.9.8 version we cannot access the settings of any user in the "Vpn and Remote Access - > Remote Dial-In" user section.
When we click on the number of the user in order to access the settings we get the error : Authorization Error ! Browser not authentication-capable or authentication failed.

This happens almost all the time and rarely sometimes we might get into the details of a user, however it seems like a bug since we haven't changed anything after the upgrade of the firmware and previously everything worked perfect.

Could you please provide us any ideas in order to fix it?
Should we try to downgrade our firmware?
 

Try this:
if your access Ip to the router is pe. 192.168.0.1 just put https://192.168.0.1/ in the browser tab. This force to you use SSL-Conection. It will be adressed as unsecure because of the Vigor certificate, but doesn't matter.
Than allow access to unsecure site and it should work.
After this you can also configure only for this site access to unsecure content to avoid to give permission ev.time toy access to it. Hope it helps.
Nick

Our default access was always through http. We never had any issues before the last firmware upgrade.
Should we switch it to force https?

Yes. I had the same issue. Always choosed http to access, but since Firmware upgrade it runs into this issue.

Btw. doesn't happen (for me) if I access inside the same subnet. Like my PC IP-adress is 192.168.0.50 and Router has 192.168.0.1.
It only happens when I access via VPN from my office to another site with another subnet. Like my PC IP-adress is 192.168.0.50 and Far-Router has 172.17.0.1.
I guess it's for security reasons.
Cheers have anice day
Nick

I tried to access our router from https, which had a different port, and everything worked.
Thanks for the reply!