Hmm, I guess I fouled up something:
Wed May 6 22:22:48 2020 daemon.err collectd[2403]: exec plugin: exec_read_one: error = sh: -want0: out of range
Wed May 6 22:22:48 2020 daemon.err collectd[2403]: exec plugin: exec_read_one: error = /usr/libexec/collectd/sqm_collectd.sh: eval: line 1: osppppoe-want0=1: not found
Wed May 6 22:22:48 2020 daemon.err collectd[2403]: exec plugin: exec_read_one: error = sh: -want1: out of range
Wed May 6 22:22:48 2020 daemon.err collectd[2403]: exec plugin: exec_read_one: error = /usr/libexec/collectd/sqm_collectd.sh: eval: line 1: osppppoe-want1=2506: not found
Wed May 6 22:22:48 2020 daemon.err collectd[2403]: exec plugin: exec_read_one: error = sh: -want2: out of range
Wed May 6 22:22:48 2020 daemon.err collectd[2403]: exec plugin: exec_read_one: error = /usr/libexec/collectd/sqm_collectd.sh: eval: line 1: osppppoe-want2=2: not found
From cat /etc/config/luci_statistics
[...]
config statistics 'collectd_exec'
option enable '1'
config collectd_exec_input
option cmduser 'nobody'
option cmdgroup 'nogroup'
option cmdline '/usr/libexec/collectd/sqm_collectd.sh pppoe-wan'
[...]
Might be related to the hyphen in pppoe-wan...