My xubuntu gateway is slowing my internet speeds

I have a box (Xubuntu) set up with iptables etc. as a gateway. It has been running for years now just fine. Recently, I noticed that my internal hosts are slow on the internet. I ran speed tests from the server AND the internal hosts.
On the Server, I am getting the 100 Mb as expected. However, on the internal hosts, I am only getting 10-30 Mb. My hosts are connected via WiFi to my network. I am using Meraki gear (MR72 and MR42). I ran some ping tests from my laptop to the AP’s:

$ ping 192.168.6.112
PING 192.168.6.112 (192.168.6.112) 56(84) bytes of data.
64 bytes from 192.168.6.112: icmp_seq=1 ttl=64 time=9.42 ms
64 bytes from 192.168.6.112: icmp_seq=2 ttl=64 time=4.82 ms
64 bytes from 192.168.6.112: icmp_seq=3 ttl=64 time=10.0 ms
64 bytes from 192.168.6.112: icmp_seq=4 ttl=64 time=3.77 ms
64 bytes from 192.168.6.112: icmp_seq=5 ttl=64 time=4.91 ms
64 bytes from 192.168.6.112: icmp_seq=6 ttl=64 time=4.48 ms
64 bytes from 192.168.6.112: icmp_seq=7 ttl=64 time=10.9 ms
64 bytes from 192.168.6.112: icmp_seq=8 ttl=64 time=10.4 ms
64 bytes from 192.168.6.112: icmp_seq=9 ttl=64 time=2.41 ms
^C
--- 192.168.6.112 ping statistics ---
9 packets transmitted, 9 received, 0% packet loss, time 8011ms
rtt min/avg/max/mdev = 2.412/6.809/10.975/3.151 ms
knichel@ORYX:~$ ping 192.168.6.104
PING 192.168.6.104 (192.168.6.104) 56(84) bytes of data.
64 bytes from 192.168.6.104: icmp_seq=1 ttl=64 time=3.42 ms
64 bytes from 192.168.6.104: icmp_seq=2 ttl=64 time=4.31 ms
64 bytes from 192.168.6.104: icmp_seq=3 ttl=64 time=2.18 ms
64 bytes from 192.168.6.104: icmp_seq=4 ttl=64 time=4.48 ms
64 bytes from 192.168.6.104: icmp_seq=5 ttl=64 time=2.12 ms
64 bytes from 192.168.6.104: icmp_seq=6 ttl=64 time=4.23 ms
64 bytes from 192.168.6.104: icmp_seq=7 ttl=64 time=2.24 ms
^C
--- 192.168.6.104 ping statistics ---
7 packets transmitted, 7 received, 0% packet loss, time 6008ms                               
rtt min/avg/max/mdev = 2.129/3.287/4.484/1.005 ms  

Ping tests to google from Server are in the 30ms range
Ping tests to google from laptop are in the 40-60ms range
I am using 8.8.8.8 & 8.8.4.4 as my nameservers and handing out dhcp addresses internally.

I have tried resetting iptables to allow everything and masquerade on my external interface and that did not help.

I need suggestions…