Integrating AsusWRT router

I’m having the Asustor AC68U running AsusWRT firmware. Now I’m trying to integrate sensors in HASS, but encountering some problems with this.
I first looked into the AsusWRT integration, but it seems I’m not able to use this, sinse I have a “_” in my admin name (Only alphanumeric characters and dash symbol are accepted. The first character cannot be a dash -).

I’m not really looking to change the admin name, because I got used to it and it’s working convenient for me. I did not knew a "_"would be given problems in future.

I’m lately also playing around with SNMP, and when I scan my router IP (SNMP turned on in AsusWRT) with MiBbrowser, I’m able to find diffrent values.
Probably the same values as AsusWRT is giving me? Not sure though…

So I was thinking setting up SNMP sensors instead of using the AsusWRT integration (and have to change the username).

I’ve configured SNMP on AsusWRT and have set “SNMP Get Community” to “public”. And left “SNMP Set Community” blank.
As mentioned, MiBbrowser is giving several values (community: public) as “. — 4 days, 13 hours, 10 minutes, 33 seconds.”.
But when configuring an router uptime sensor in HASS, directed to the router IP and using the above SOID, I get an value of “39661766” instead of the days, hours, minutes, seconds format as stated above.

# Asus RT-AC68U sensors
- platform: snmp
  name: Router_Uptime
  community: public
  version: 2c
  accept_errors: true

Annyone an idea of getting around these problems?