Uh oh. That screenshot looks seriously like an Asus.
Unfortunately, the data that an Asus presents is somewhat confused, so makes it impossible for people to offer serious guidance (beyond the questions about the physical copper pair).
Some people love the Asus routers, but the generic evidence suggests they just aren't very good as VDSL2 modems.
I'd recommend that you beg, borrow, steal or buy something else. Anything else. If you have to buy something, and you think your line is likely to continue to have problems afterwards, it makes sense to buy something that is compatible with programs that can read and monitor the line statistics from the modem. If you want to keep the Asus as a router, then you need a box that can be configured to work as just a modem.
Ones with a Broadcom chipset seem a good start: http://forum.kitz.co.uk/index.php/topic,14436.0.html
I'm currently using the Billion 8800NL.
DSLStats and HG612-modem-stats are regular monitoring programs, with advice available:
Having said all of that, FTTC's range does seem to be most limited by the upstream. More so if the line is aluminium, or partially so. Your line could well be like this, and the problem is nothing to do with the Asus.