There is a config repository for LANCOM: https://github.com/opennms-config-modules/lancom-lcos

If there's anything I can test or further investigate, please let me know. By now, the traps I generated should have been covered by the XML but apparently aren't. But as far as my guesses regarding MIBs go, the subcategories at least overlap.

Here I found some information about which traps LANCOM routers send via SNMP: https://www2.lancom.de/kb.nsf/bf0ed2a4d2a4419ac125721b00471d85/c1256ce800362567c1256b6f00310ee6?OpenDocument

Here, the VDSL line went up again after I intentionally pulled the connector:
26.05.2016 17:56:47 router1 192.168.1.1
uei.opennms.org/generic/traps/EnterpriseDefault Edit notifications for event
Received unformatted enterprise event (enterprise:.1.3.6.1.4.1.2356.11.8.609.0 generic:6 specific:78). 4 args: .1.3.6.1.2.1.1.1.0="LANCOM 1781VA (over ISDN) 9.10.0530 / 09.12.2015 4003509832100573" .1.3.6.1.2.1.1.5.0="router1" .1.3.6.1.4.1.2356.11.1.35.1.1.3.6.78="13" .1.3.6.1.4.1.2356.11.1.75.1.0="5"

Strangely enough, outage of the VDSL line was not sent via SNMP traps, although the router logged it in its internal log.

Ah, I meanwhile read about the reason for DNS down discovery.

So, I start to receive traps, I did a quick login/logut via SSH, which is displayed as unformatted events:

15862 22.05.16 11:54:39 Normal Received unformatted enterprise event (enterprise:.1.3.6.1.4.1.2356.11.8.609.0 generic:6 specific:10). 7 args: .1.3.6.1.2.1.1.1.0="LANCOM 1781VA (over ISDN) 9.10.0530 / 09.12.2015 4003509832100573" .1.3.6.1.2.1.1.5.0="router1" .1.3.6.1.4.1.2356.11.1.35.1.1.3.6.10="2" .1.3.6.1.4.1.2356.11.1.11.12.1.7.1="05/22/2016 11:54:43" .1.3.6.1.4.1.2356.11.1.11.12.1.2.1="10" .1.3.6.1.4.1.2356.11.1.11.12.1.3.1="7" .1.3.6.1.4.1.2356.11.1.11.12.1.8.1="192.168.1.5"

15861 22.05.16 11:54:37 Normal Received unformatted enterprise event (enterprise:.1.3.6.1.4.1.2356.11.8.609.0 generic:6 specific:9). 7 args: .1.3.6.1.2.1.1.1.0="LANCOM 1781VA (over ISDN) 9.10.0530 / 09.12.2015 4003509832100573" .1.3.6.1.2.1.1.5.0="router1" .1.3.6.1.4.1.2356.11.1.35.1.1.3.6.9="2" .1.3.6.1.4.1.2356.11.1.11.12.1.7.1="05/22/2016 11:54:40" .1.3.6.1.4.1.2356.11.1.11.12.1.2.1="9" .1.3.6.1.4.1.2356.11.1.11.12.1.3.1="7" .1.3.6.1.4.1.2356.11.1.11.12.1.8.1="192.168.1.5"