Hi,
I tried dropping the MTU on the WAN by setting max_mtu and max_mru to Like what @Roger said. Use this for your MSS
Change ether1-gateway for pppoe interface if that what you are using for your WAN interface. /ip firewall mangle add action=change-mss chain=forward comment="MSS Clamp" in-interface=ether1-gateway new-mss=1400 passthrough=yes protocol=tcp tcp-flags=syn tcp-mss=1401-65535 add action=change-mss chain=forward new-mss=1400 out-interface=ether1-gateway passthrough=yes protocol=tcp tcp-flags=syn tcp-mss=1401-65535 -----Original Message----- From: Public <public-bounces@talk.mikrotik.com.au> On Behalf Of Karl Auer Sent: Saturday, 9 April 2022 10:16 AM To: MikroTik Australia Public List <public@talk.mikrotik.com.au> Subject: Re: [MT-AU Public] Odd IMAP failures, seems to be network On Fri, 2022-04-08 at 16:44 +1000, Denis Hancock wrote:
Try dropping the MTU on the WAN
I tried dropping the MTU on the WAN by setting max_mtu and max_mru to 1280 on the PPPoE client interface. 1280 because anything less and IPv6 stops working. Most things continued to work fine but a few things did not: - The AWS login screens would not load (Console and SSO) - my OpenVPN VPN would not connect - GoogleMail (web interface) would not load Not sure what I did wrong there, but when I put it back to the value it had before - 1480 - everything worked again. I'll give it another try later on and disconnect/reconnect all PC network interfaces in case they were "remembering" stuff. Regards, K. -- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Karl Auer (kauer@nullarbor.com.au) work +61 2 64957435 http://www.nullarbor.com.au mobile +61 428 957160 _______________________________________________ Public mailing list Public@talk.mikrotik.com.au http://talk.mikrotik.com.au/mailman/listinfo/public_talk.mikrotik.com.au