PPPoE-server does not allow listening to interfaces without tags if tags are present in the configuration.
For example, we want to get PPPoE-server on `eth1` (without tags) and on additional VLANS `10-122`
I.e., the listen interface should be:
eth1 / eth1.10 / eth1.11 / eth1.xxx / ... / eth1.122
But it is impossible with the current CLI (eth1 without tag)
```
set service pppoe-server access-concentrator 'ACN'
set service pppoe-server authentication mode 'radius'
set service pppoe-server authentication radius server 127.0.0.1 key 'xxx'
set service pppoe-server client-ip-pool FIRST range '100.64.0.0/24'
set service pppoe-server gateway-address '100.64.0.1'
set service pppoe-server interface eth1 vlan '10-122'
set service pppoe-server interface eth1 vlan-mon
```
Generated configuration:
```
vyos@r14# cat /run/accel-pppd/pppoe.conf | grep '\[pppoe\]' -A 5
[pppoe]
...
interface=re:^eth1\.(1\d|[2-9]\d|1[0-1]\d|12[0-2])$
vlan-mon=eth1,10-122
```
To fix it, I have to add manually to the `pppoe.conf ` the option `interface=eth1`
```
vyos@r14# cat /run/accel-pppd/pppoe.conf | grep '\[pppoe\]' -A 5
[pppoe]
...
interface=re:^eth1\.(1\d|[2-9]\d|1[0-1]\d|12[0-2])$
vlan-mon=eth1,10-122
# my manual change here
interface=eth1
```