I see that you have a modem/router with a
Broadcom chipset and you are now connected to a MSAN with an
Infineon chipset.
Things are looking good for you but it's still early days and you should let it "settle down".
The only advice I'll give at this moment is to disconnect the modem/router from the xDSL and, thus, allow the MSAN to have some "quiet quality time" on its own. (Perhaps an hour.) Whilst the modem/router is disconnected, take that time to go through and check all of its settings. For example, does it have an xDSL mode setting? Perhaps
G.Dmt,
ADSL2,
ADSL2+ and
Auto could be the options available. You might like to try either forcing
ADSL2+ or
Auto, depending upon how it is currently configured.
Once you have reconnected the modem/router to the xDSL, resist the urge to "fiddle".